Donald Farr
Former Editor, Mustang Monthly
June 1, 2009
Photos By: The Mustang Monthly Archives

"Matching numbers." We hear it all the time. It's tossed out proudly by car owners at shows. We see it used as a selling point for Mustangs for sale in classified and website advertisements. Even Speed TV commentators describe high-dollar Mustang muscle cars as "numbers matching" during televised, high-profile collector car auctions.

But what does it mean for '65-'73 Mustangs, and does it really have an affect on a car's desirability, collectability, and value?

The metal door data plate on '65-'69 models provides the most important numbers on a Mustang, including stampings for the VIN and codes for the engine, body style, interior trim, exterior color, build date, sales district, transmission, and rearend. Experts can spot whether or not a data plate has been replaced by the rivets.

According to Wikipedia, "numbers matching" comes from the collector car market to describe "the authenticity of collectible or investment quality cars, generally meaning that a particular car still has its major components or has major components that match what the car had when it was new." Major components are listed as the frame, engine, transmission, and rearend, which, in some cases, have the car's Vehicle Identification Number (VIN) stamped in them. To concours judges and collectors, especially those who deal with desirable Mustangs like Shelbys and Bosses, the meaning can go much deeper, right down to casting numbers and date codes on individual parts.

"Matching numbers can even get into how everything matches the build sheet and buck tag," says Ed Meyer, a noted Mustang judge, restorer, and expert on factory originality. "It's from bumper to bumper- even the bumpers are dated. The taillight buckets on '69s have a code for when they were assembled. Wiring harnesses have ID tags. There were tags on the seats with a date code; you can't see them unless you take the springs out. They had to have all that stuff in case there was a problem so they could trace it down."

In 1970, the metal door tag was replaced by a Mylar vehicle certification label, which includes the same basic information as earlier metal tags. Unfortunately, the typed lettering on these labels is prone to fading, making the codes difficult to read. In many cases, the labels have been painted over during repaints.

Corvette enthusiasts were likely the first to place such importance on matching numbers. When Corvette owners and restorers began taking cars back to original condition, they used the various ID and date-code stampings to determine if the car and its parts were original. As other vehicles reached collectible status, the matching numbers game spilled over into the Thunderbird, Mustang, and collectible musclecar hobbies.

What Does It Mean?
In its most basic form, a matching numbers Mustang has a metal door data plate ('65-'69) or Mylar vehicle certification label ('70-'73) with a VIN that matches the VIN stamped into the inner fender apron, as seen with the hood open and located in a fender cut-out on the driver's side. Because the VIN includes the engine code, you can also take it to mean that the engine must be the correct type for the car. For example, a '67 Mustang with a later 351 Windsor engine would not be considered numbers matching. The data plate (sometimes called warranty plate) also includes codes for the body style, exterior color, interior trim, scheduled build date, transmission, and rearend axle ratio, so those items are also considered in the matching numbers identification. On '68-'73 Mustangs, the VIN on the data plate and inner fender should match the VIN on the windshield VIN tag, which was mandated by the federal government beginning with '68 models.

Matching numbers have become extremely important to collectible high-performance Mustangs like Shelbys, Bosses, and Cobra Jets. You'll hear the term used often at collector car auctions.

Over the course of four decades, most of today's surviving '65-'73 Mustangs have experienced any number of misfortunes. Many don't have their original engine due to service replacement or a performance swap. Damaged original doors have been replaced with good doors (and data plates) from other Mustangs. Cars with heavy front-end damage have been "clipped," meaning their front-end assemblies (with the stamped VIN) have been replaced with front-ends from wrecking yard donors. In the last two examples, the door data plate won't match the stamped inner fender VIN. Sometimes, data plates are missing entirely. On the later '70-'73 Mustangs, Mylar certification labels are often faded beyond readability or painted over. So there are any number of reasons why a Mustang may not be numbers matching today.