Real or Fake ’66 GT?

How to tell them apart

The information on this page applies to 1965 and 1966 GT Mustangs only. This is a list of information that we have collected over the years. To the best of our knowledge, it is both true and correct. However, we offer this for informational purposes only. We have learned over the years that nothing is 100% with a Mustang, so we will not be held accountable for you buying a 6 cylinder coupe that someone “turned into a GT”. We hope you find this information valuable.66GT


1. There is no such thing as a 1964 1/2 GT. That means if you car has a generator, then it is not a GT.

2. All GTs had 4 barrel carburettors. This means your engine code in the V.I.N. had to be:
a. A=289 4v
b. K=289 Hi-po

3. All 1965 “K” code GTs had manual transmissions. 1965 “A” code GT’s could have been automatic or manual. All 1966 GT’s could have been automatic or manual.


1. All GTs were equipped with the special handling package which consisted of:
a. Stiffer Springs
b. Heavy Duty Shocks
c. 13/16″ Front Sway Bar
d. Quick Ratio Steering Box (Code: HCC-AX for Manual Steering and HCC-AW for Power Steering)


1. Instrument panel would have included the gauges instead of the “idiot” lamps:
a. 65 – this would have been an upgrade option.
b. 66 – all cars had gauges.

2. 1965 GT’s had a unique amp gauge with a pass through amperage sensor. This is different than the standard 1965 Mustang amp gauge.

All 1966 Mustangs have the same amp gauge that receives a charge/discharge signal from the voltage regulator.

3. There were two different sets of instrument bezels and glove box doors that came on 1965 and 1966 Mustang GT’s:

GT Deluxe Pony Interior

Pony GT dashglove

GT Standard Interior

st gt dashglove

4. When the fog light switch is activated on a GT, the rear tail lights will also turn on.

Aftermarket fog light switches and wiring harnesses do not accommodate this feature.

5. GT’s include a relay with constant power mounted on a tab near the support brace for the brake pedal.


1. Originally equipped with front disc brakes.

2. Requires a proportioning valve.

3. Because of the dual exhaust, the rear brake hose mounts in a higher location in the arch of the axle housing then the single exhaust. This is to prevent the rear brake hose from being burned by the exhaust pipe.

4. Mustangs with disc brakes had a much larger master cylinder then those with drum brakes. The pictures show the difference between the two master cylinders.


1. Dual exhaust was standard and exited the rear of the car through the rear valance.

2. There are reinforcing plates for the exhaust hanger studs on each side of the tunnel under the rear seat floor pan.

3. There are two bolt holes punched through the rear end of the rear frame rails. They are for the exhaust hanger brackets that support the trumpets on each side of the car. These holes can not be drilled after the car is welded together because the trunk floor is in the way.

4. The rear frame rails also have a “U” shaped reinforcement piece inside the frame rail where the holes for the rear exhaust hangers are. This reinforcement can be felt by placing your shortest finger in the rear alignment hole in the frame rail and tipping it rearward.

5. The rear brake hose body hanger was moved from the top of the driveshaft tunnel to vertical section of the rear floor (drivers side), between the rear exhaust hanger holes and the frame rail. There is a vertical and horizontal indention in the vertical floor section to identify the correct placement.



1. “GT” emblems are mounted on each of the front fenders and the running horse emblems were deleted.

2. Individual “M U S T A N G” pin letters are located in a stripe that runs along the lower rocker panel.

3. 1966 Mustang GTs came with a “GT” logo gas cap.

4. Rocker panel mouldings are excluded.

5. Fog lights are standard.

6. The holes in the radiator support for the fog lights are punched through the support, not drilled.

Therefore, if the fog lights are factory installed, there should be a lip on the hole in the radiator support, not a clean drilled hole.

7. Chrome hood mouldings are standard:
a. 65 – this would have been an upgrade option.
b. 66 – all cars had hood mouldings.

This information is for information only, so please check any validation of a GT carefully before you buy. If anybody has anything to add or amend on here please let me know.


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