Early Mustang Production History and Historian Bob Fria's Findings
The Fria Files: Mustang Historian Robert “Bob” Fria has spent nearly two decades researching how Mustang production began a half century ago. Here are his findings
Retired airline captain, and respected Mustang historian, Bob Fria, is best known for his fierce commitment to history, because no one has researched early Mustang production to the degree he has or for as long. Captain Bob has been researching the coveted low serial number launch Mustangs ever since he purchased 5F07U100002, the first production Mustang hardtop, in 1997. It has been through Bob’s efforts that we know as much as we do about how Mustang production began early in 1964 in two Ford assembly facilities in Dearborn and Allen Park, Michigan.
Bob has shared his findings and theories with Mustang Monthly. Together, we’re going to sort this research out, to help shed more light on how Mustang production began. It has taken years to amass this information, including interviews with dozens of people, including Ford insiders and owners of pilot, pre-production, and early mass production Mustang units produced between the summer of 1963 and April of 1964.
It has long been written by Ford historians and journalists alike that Mustang production began on Monday, March 9, 1964 at Ford’s Dearborn, Michigan, assembly plant with 5F08F100001. This is the greatest Mustang fable ever told—and it is largely untrue. Though Monday, March 9, 1964 is widely recognized as the official first day of Mustang production—and it was—the 5F08F100001 part of this oft’ told story has never been true and here’s why.
Prior to the March 9 launch date, Ford built approximately 180-200 pre-production Mustang units with date codes of 05C. The 05C date code does not mean Thursday, March 5, but instead it is an arbitrary date code used to identify or flag pre-production units at a glance amid the chaos of Ford’s most successful product launch ever. Consecutive unit numbers on these 05C Mustangs run from 100001 to approximately 100180. The highest 05C consecutive unit number found to date has been 100178, located in Britain with an export 90-99 DSO code.
The lowest known 09C date code (March 9) consecutive unit number is 100211, a six-cylinder hardtop located in North Carolina. Somewhere in all of this data is the dividing line between 05C and 09C cars, which is not known at press time, but we’re getting close to an answer, thanks to Bob’s efforts. Bob’s research gives us a close and tentative dividing line between pre-production 05C Dearborn Mustang units and mass production 09C units. Based on known information at press time, the dividing line is somewhere around 100180-100200, though this has never been confirmed. The identity of Job 1, March 9, 1964, has never been confirmed either, though the white convertible story remains popular.
Bob went to work in search of greater detail, because still not enough was known about how Mustang production began and how his first production hardtop and others like it fit into the big production picture. Bob stresses most of this data is concrete information based on Ford documentation and interviews interspersed with strong theory from what he has learned based on what is known at the present time. The theory seems credible based on research backed by Ford documentation and hundreds of interviews.
“By March 5, 1964, all 180-200 pre-production Mustang units had been built, all with consecutive unit numbers of 100001 to approximately 100180,” Bob confirms. “As the owner of 5F07U100002, I had access to information specific to this pre-production car. I was also able to contact owners of other pre-production units built for special uses, export, engineering exercises, and promotional purposes.” Bob had access to Ford Motor Company documentation that included vehicle identification numbers and purpose, which led him to even more specific information that brought most of the pieces of the puzzle together. What Bob has learned in his research is remarkable.
Ford’s Pilot Plant in Allen Park, Michigan, south of Dearborn and just off the Southfield Freeway was conceived to build pre-production “pilot” units to establish assembly procedures and make engineering revisions as necessary. The pilot plant, which is a scaled down assembly line, allows Ford manufacturing personnel to make corrections before the complexities of a chaotic mass production assembly line.
According to Bob, it appears at least 15 Mustang pilot units with S-code pilot plant VINs were produced at Allen Park before assembly began at the Dearborn plant between January and March of 1964, though a total number has never been confirmed. Where this story takes on a bizarre twist are “gray area” Mustang bodies that were bucked and welded together at Allen Park, then shipped to the Dearborn plant and assembled as pre-production Mustang units. The late Bob Negstad, a Ford chassis engineer, confirmed some pilot plant Mustang bodies were transferred to the Dearborn Assembly Plant and serialized as Dearborn plant vehicles. Bob’s 5F07U100002 pre-production car was identified by Negstad to be one of them.
Bob’s investigative work began with his own 100002 pre-production hardtop, which had different manufacturing nuances than other Mustangs he had seen and restored. He took his hardtop down to bare steel, removing all paint and body sealant, remaining faithful to the car’s original state. There were odd pilot stampings, stick and wire-feed welding instead of factory spot welds, modified seams and joints, “pilot part” labels, evidence of cutting torch use, and a host of other issues that made his six-cylinder hardtop different than anything he’d ever seen. The car had never undergone a full-scale restoration before.
When Bob interviewed Ford manufacturing engineers who were directly involved in the Mustang’s launch, he learned a lot about the oddities that made his 100002 car anything but ordinary. Across his Mustang’s floorpan was a long weld that tracked over the transmission tunnel. Turns out the floorpan stamping die tended to crack the floorpan at the tunnel, which called for modification of the stamping die, according to Ford insiders Bob had spoken with. Meanwhile Bob’s cracked floorpan had to be welded up with a wire-feed welder to repair the crack. So did other pilot and pre-production units.
Bob became curious about other 05C pre-production cars like 100003, 100004, 100005, 100006, and so on. Through sheer luck and a lot of investigative work, Bob managed to find 100004, 100006, 100047, 100129, 100140, 100143, 100145, 100155, 100170, 100173, and 100178. Additional good fortune put Bob in direct touch with the people who owned most of these cars where he could glean detailed information about each unit.
Radiator Support Codes
Bob noticed handwritten codes etched in his Mustang’s radiator support, which every early Mustang has. These codes were one form of communication for assembly workers indicating paint and trim color, options, and even line positioning sequence.
When Bob was researching his excellent Mustang Genesis book, he learned a lot about Mustang production startup at the Dearborn Assembly Plant from Ford engineers and management types who were there during the launch. Information from other owners of pre-production units inspired Bob to move toward a closer study of radiator support codes. As he accumulated data from each of these pre-production and early mass production units, a startling discovery was made—a very distinct pattern of alphanumeric inventory control codes that were a light bulb moment for him. Bob became convinced he had finally cracked the code, a way to establish an actual physical order of pre-production units as well as pilot units.
“On the righthand side of the radiator support of nearly every Mustang assembled at the Dearborn Assembly Plant through at least April 20, 1964 are four, sometimes five, lines of production codes,” Bob tells Mustang Monthly. “These codes were always handwritten between the radiator support opening and the battery cooling vents.” These codes, Bob adds, were handwritten with a marker. Through electrolysis between the paint material and the raw steel, these codes eventually became permanently etched into the metal. Radiator supports were then painted, which concealed this information, but did not eliminate it. It should still be there if your radiator support hasn’t been sanded or media blasted.
“The first or top line of these codes is an alphanumeric code, a letter and a number, such as ‘A15’ or ‘B37,’” Bob tells us. “This code is apparently derived from a sequencing code program used by the plant’s build scheduling office—an inventory control number tied to a specific vehicle identification number.” This alphanumeric inventory sequencing code is on par with what is more widely known as the “rotation” number, which is an assembly line locating number that enables plant personnel to locate specific units on the line. VINs rarely indicate physical position of Mustang units on the assembly line, hence the need for rotation numbers.
There have traditionally been two rotation numbers in Ford vehicle production since late in the ’65 model year, one for the body line and another for the trim and chassis line where the car was actually assembled. The body line rotation number is located on the body buck tag, which was first used late in the ’65 model year at Dearborn and Metuchen, New Jersey, plants only. It was also written by hand on both sides of the radiator support. The San Jose, California (Milpitas), plant used body buck tags for a very short time in the ’70 model year and never used them again.
The trim and chassis rotation number was located on the broadcast sheet. Rarely were the two rotation numbers ever the same because we’re talking two different lines. In fact, the body line should be viewed as a separate plant entirely. The body line is where steel stampings are welded together to create a car body along with preparation and painting. When a painted body enters the trim and chassis line, it gets a trim and chassis rotation number. Rotation numbers are unit location numbers as bodies and assembly jigs “rotate” through the assembly line. They begin at 001 and end at 999, then start over again at 001. Today, the trim and chassis rotation number is a four-digit number. It is believed body buck tags and broadcast sheets arrived during the ’65 model year with the advent of IBM punch cards and a more efficient accounting system.
What makes these ’64-era alphanumeric inventory control rotation codes different than line rotation numbers is their alphanumeric letter/number combination. It appears the letter means the phase of pre-production and mass production, with first phase being A, then B, and then C before starting over again at A with mass production on March 9, 1964.
Once mass production began on March 9, the A phase led to B phase, then C phase, and then D phase, and so on. It is believed, but not confirmed, each phase began with 001 leading to 999, then, started over again with a new letter and 001. This pattern appears very consistent across a wide range of early ’65 Mustangs before the duo system of rotation numbers began. And if this fails to foster confidence in this theory, there are also Dearborn-built ’64 Fairlanes with the same alphanumeric rotation code. In reviewing Ford assembly line images elsewhere in the system, the alphanumeric inventory control code existed prior to 1964.
Based on the data Bob has accumulated from a cross section of pre-production Mustang units, there is a pattern that begins with A12 on 5F08F100001, then A15 on Bob’s own 5F07U100002 car, 5F08F100004 is B3?, as is 100047 with a B3? code. Of particular interest to Bob is 100129 with an alphanumeric code of B40, which follows the B3? code numerically. These B3? lack the second half of the number because they could not be read. However, these alphanumeric codes follow a sequence giving Bob’s research substance. There’s credibility in this sequence.
|Pre-Production 05C Sequence|
|Dearborn Plant Consecutive Unit||Inventory Control Rotation Code||Date Code||Vehicle Location|
|100001||A12||Henry Ford Museum|
|100047||B3?||05C||Ford Documentation and present owner interview|
|100129||B40||05C||Owner Chris Lemp and Ford Documentation|
|100140||C9||05C||Bruce Beeghly, Ohio|
Reviewing this table, you begin to see a pattern of alphanumeric inventory control codes, which are actually rotation numbers that physically place each Mustang unit on the assembly line in order beginning with A1, A2, and A3, and so on. As you can see 100001 is A12 and 100002 is A15, meaning there were conceivably two units built between 100001 and 100002, though this cannot be confirmed. It can also mean A1 through A11 came ahead of 100001 and 100002. The VINs of the A13 and A14 units are not known, but likely tied to paint and trim colors/codes more than anything. In other words, units were normally scheduled and lined up per paint and trim colors for simplicity in the body plant more than anything. It makes more sense to paint several units in the same color, clear the paint guns, and begin using a different color on another grouping of identical color units.
At 100004 and 100047 note the rotation code of B3? or Phase B. The B and 3 are legible, yet the third character/number is not. The third character remains a mystery because it is distorted and cannot be read. Because 100003, 100004, and 100005 were all New York Worlds Fair cars and all Raven Black, all probably had consecutive inventory control/rotation numbers.
Mustang unit 100006, which is also a World’s Fair Magic Skyway car like 100004, is undergoing a longterm restoration in Georgia. Its current status is not known. Because 100006 was found in a South Georgia salvage yard in rusted-out condition and missing its radiator support, the alphanumeric inventory control/rotation code is not known. Because 100007 and 100008 were also Wimbledon White like 100006, they likely had consecutive inventory control codes.
Where Bob’s research takes an interesting twist is 100129 with B40 and 100140 with a rotation code of C9, then, 100170 with C19 meaning Phase C, unit 19. Bob has clarified the way Ford did inventory control/rotation sequencing prior to the split system of body and trim line rotation numbers.
It is important to remember that the Dearborn Assembly Plant shut down in early February of 1964 to prepare the line for the simultaneous production of Fairlane and Mustang. It resumed operations February 10. And this is where production sequencing gets a bit dicey, because it remains unknown exactly when pre-production Mustang assembly ended. We do, however, know mass production began officially on March 9, yet we don’t know the VIN or the alphanumeric inventory control/rotation code of Job 1 or even the first mass production unit scheduled. Knowing both is key to learning the true identity of the first 09C unit scheduled for assembly. At press time, we still don’t know the last 05C VIN, nor do we know the first 09C VIN. What’s more, we need to know the rotation code of each for an accurate conclusion to this enduring mystery.
Bob Fria has compiled a list of known pilot plant Mustang units with S plant code VINs. This information is based on Ford photographs of pilot units where the VIN is clearly verifiable and there’s legitimate Ford documentation from the period.
The earliest pilot unit Bob has found is 4S07X000000; a VIN stamped into the shock tower of a Mustang he believes was bucked in the summer of 1963. What Bob has yet to sort out is how 4S07X000000 segued to the 5S pilot plant units. In other words, how many 4S and 5S pilot units were produced? It may be the 4S was used before it was decided that all Mustangs would be 5S, ’65 model year cars. It is theorized this 4S chassis is a one-of-a-kind prototype sent to and used by the pilot plant to set up the initial chassis run of pilot cars.
It is Bob’s belief, based on his own research, that at least two of these pilot units were shipped to Dearborn Assembly and serialized as pre-production cars. Bob’s belief is 5S08F100012 was re-serialized as 5F08F100001 and 5S07U100015 was re-serialized as 5F07U100002 based on the inventory control codes found on the radiator supports. It is unknown how many S-code pilot plant units were produced, nor how many pilot plant Mustang bodies were transported to the Dearborn Assembly Plant to be serialized and assembled as pre-production units.
These were pilot cars, and some had to have been damaged, destroyed, or rendered scrap according to program testing. Certainly not all pilot cars were sent to the Dearborn Assembly Plant to be built and re-serialized. Until more 05C pre-production units surface, it is theory as to how many pilot chassis were sent to DAP to be built as pre-production cars. If you own a 05C pre-production Mustang, we’d like to hear from you along with complete information from your warranty plate, inner fender, and most importantly radiator support markings, and sheetmetal stamping date codes.
|Known Pilot Plant Information|
|VIN||Model||Theoretical Inventory||Notes||Control/Rotation Codes|
|5S08K100002||Convertible||A2||Documented as Mustang III Concept Car per Ford; likely an error. Scrapped at Holman-Moody, Charlotte, NC|
|5S07X100003||Hardtop||A3||Shipped to Alan Mann Racing, England for race testing, scrapped|
|5S08F100006||Convertible||A6||Scrapped, Dearborn Steel Tubing|
|5S08F100008||Convertible||A8||Scrapped, Dearborn Steel Tubing|
|5S08F100009||Convertible||A9||Mustang III Concept Car built by Dearborn Steel Tubing. In private ownership today|
|5S08F100010||Convertible||A10||Scrapped, Dearborn Steel Tubing|
|5S08F100012||Convertible||A12||Shipped to DAP, Assigned VIN 5F08F100001|
|5S0XX100013||Unknown||A13||To General Marketing Operations for AK Miller racing||To General Marketing Operations for AK Miller Racing|
|5S08F100014||Convertible||A14||Scrapped, used by Jacque Passino as Performance Project #12M-81|
|5S07U100015||Hardtop||A15||Shipped to DAP, Assigned VIN 5F07U100002|
In Bob Fria’s extraordinary archives is this official Ford Shop Manual supplement dated March 16, 1964, titled “1964 Mustang.” Because the Mustang went from concept to mass production in a scant 18 months, there were assorted mistakes and misconceptions, including this Shop Manual supplement.
Monday, March 9, 1964 was the official first day of Mustang mass production, though it did not begin with 5F08F100001. The earliest known 09C car remains 5F07U100211 with a DSO of 22 for Charlotte, North Carolina, where this car remains today. Next in line is 5F08F100212, a Wimbledon White convertible with a 09C date code. Bob’s research has included 09C and beyond early production cars. What he learned can be found in the accompanying sidebar.
Mass Production Quick Facts
Alphanumeric inventory control/rotation codes continue after pre-production ends with the same predictable pattern. Here’s a sampling of early Mustang units assembled at the Dearborn Assembly Plant.
|VIN||Model||Inventory Control or Rotation Code||Date Code|
|100280||Convertible||B16 or B26 (Illegible)||10C|
Talk To Bob
If you’d like to correspond with Bob Fria about your low-number production Mustang, he invites your contact. You can email Bob at email@example.com.