1966 Ford Mustang Grille Fog
Bob Aliberto
January 22, 2014

Fog Light Wiring

I have purchased a disassembled ’66 Mustang. During reassembly, I ordered new fog light wiring from Virginia Classic Mustang. However, I cannot find information about how and where to run the wiring. Where does it go through the radiator support? Also, how do I connect the underdash wiring?

John S. Cowart

Texarkana, TX

The fog light wires go through the radiator support next to the wire grommets for the horn wires. Exact placement is not crucial as many cars had dealer installed fog lights as well as over-the-counter owner installations. Factory equipped GT Mustangs have also proven to vary. The remaining gray wiring harness runs along the driver’s side engine compartment and hood hinge area. The headlight harness plug is located there, and the fog light wire should be above that.

The underdash wiring is straightforward as it simply plugs in. There are three wires on the fog light switch. Grey goes to the fog lamps and plugs into the grey wiring harness that runs through the firewall. The blue/black stripe wire is power and connects to a circuit breaker mounted on the windshield wiper bracket. The other side of the circuit breaker should have a short blue/black lead that plugs into an existing blue/black plug on the underdash harness, which is factory provided for this purpose. The third wire is black to power the taillights so they will come on when the fog lights are switched on. This black wire ends in a harness plug that interrupts the connection between the rear taillight body harness connection behind the driver’s side kick panel. Separate the two harnesses and insert the new fog light jumper harness between the two.


T-10 or Top loader?

I have a question concerning the choice of transmission for my ’65 Mustang, which is equipped with a 289 and a T-10 four-speed transmission. I am rebuilding the 289 to produce about 320 horsepower. While I am inclined to keep the T-10, I wonder if I might be better off with a Top Loader four-speed for toughness and smoother shifting. Is it possible to say which transmission is best for my application? The car will only see spirited street driving and not the track.

James Vela

Via the Internet

I would continue to use the T-10, as it is an excellent transmission and also original to the car. Although the Ford Top Loader is a bit tougher, the T-10 is a proven performer. It was standard equipment for the ’65-’66 Shelby G.T. 350 and early Cobras, and also used by other car manufacturers as well.

One common complaint with the T-10 is gear jump-out under deceleration, with the transmission popping into neutral during heavy engine braking situations. The problem is too much endplay in the gear set. Ford sold a package of snap rings with a variety of thicknesses so technicians could select the proper snap ring to tighten up the endplay as a repair.

T-10s remained in production and a version is still produced today. Synchronizers have been redesigned to help prevent gear jump-out; they will fit early transmissions. The new design synchronizers and a tight rebuild will eliminate the jump-out issue.


Ragtop Rear Window

Can you suggest a repair for the rear window in my ’65 GT convertible short of replacing the entire top? The top is in reasonably good condition except the folding glass rear window has separated in the middle.

Bob Hughes

San Jose, CA

The convertible top’s rear window can be changed without removing the entire top if the existing zipper for the window can be left intact. The zipper is attached to the rear top bow before the top is stapled over it, therefore the top is typically removed to get at the zipper underneath. The problem is that the zipper on replacement windows rarely matches the old one remaining on the bow. Even if it does match, once zipped in, the replacement window is usually not centered properly. The fix is to have the zipper removed from the old window and reinstalled on the new window, centering it as it is sewn in. The bottom of the window has its own tacking strip and will not present a problem.


Driveshaft Compatibility

My kids and I have purchased a ’67 Mustang with a six-cylinder engine. We have converted to five-lug wheels with disc brakes up front and an 8-inch rearend. We want to drive the car for a while with the original six-cylinder. What driveshaft and u-joints should we use? We have the original driveshaft for the six-cylinder and three-speed transmission.

Jeff Ealy

Via the Internet

The original driveshaft should work as it is the proper length. However, u-joint compatibility may be an issue. There are two different sizes of u-joint bearing caps. A trip to your local auto parts store and some patience is all that will be required.


Let us hear from you. Send your ’65-’73 Mustang questions to: Beyond Basics, c/o Bob Aliberto, P.O. Box 205, Salt Point, NY 12578. Send email to mustang.monthly@sorc.com.