Hi everyone. This is my first post here on this site. This is my question. I might buy a 1966 mustang with an auto transmission and the inline 6. I don't have money to convert to V8 and not really a desire to. Is it possible to take the C-4 out and put an overdrive 4 speed auto in? I am looking to use on the freeway and would like to get better fuel economy. I tried to search on this forum but didn't come up with anything. I figured you guys would know much more than me. I know it is possible with the V8 with some minor mods but the straight 6 is what mine will have. Thanks for any help you guys/gals can give.

 

Ron,
All things are possible and the cost depends on the parts you have and your ability to scrounge parts and buy inexpensive, good quality parts.
You will need:
1. pilot bushing
2. Flywheel
3. bell housing
4. clutch cover and plate
5. throw-out bearing and collar
6. Z-bar, clutch pedal, link, adjuster link and both end bearing for the Z-bar
7. Transmission
8. shifter, handle and install plate
9. shifter linkage and bushing kit
10. possible drive shaft and u-joints
11. shifter boot, floor plate and ****

The hard part will be to find the parts for a 6 cylinder.
There is also the fact that an OD transmission will place a load on the engine at an rpm that may actually reduce your mileage. You may have to change the rear gears to make it work. The carburetor has to be out of the low torque, idle and idle transfer range of the carb in order to lean the mixture from the idle to the cruise circuit. When your engine is at 2000 - 2200 rpm you will be making enough torque that you won't be opening the power valve every time you step down slightly on the throttle and the carb will be in the cruise circuit. Around town you can keep it in the lower 3rd gear and not hurt power and mileage.

If it was me I would replace your C4 with a 1973 or later model and fit it with a TransGo 40-2 reprogramming kit. That will allow you to manually shift to second and first gear at any time and still allow you to be lazy and let it shift auto by placing it is Drive. Leave the gears alone and put on a set of headers and good exhaust. Later if you decide you want a bit more power then go to a recurved DS II electronic distributor and have the intake log milled and fitted with a Ford two barrel 2100 carb (flush mount). While the head is off (and if the engine is in good shape) you can mil the head for a bit more compression. (if the engine needs help then rebuild and use flat top pistons to bring the compression to 10:1. A bit of a cam (200 - 210 duration max) will really wake that six up.

Paul

 

Paul, he's talking about AOD, not T-5. I don't know the answer, but google "AOD 66 mustang 6 cyl" and you'll get plenty of reading material.

 

Thanks guys. It seems like it can't be that hard but then again, I just don't know. Obviously if this was the V8 then it would make things easier. I will do some more research and see what I find.