Q: I have a 1973 Mustang fastback that I have restored with the help of parts from Summit Racing. It has an FMX transmission, which I would like to swap for an overdrive automatic. Is this possible? Can you tell me which AOD four-speed will hook up to my 351 Cleveland engine?
A: We hate to be bearers of bad tidings, but the AOD is not the best choice for you. There are three reasons for this. In our opinion, a stock-form AOD can’t handle the torque your 351C produces. Then there is the flywheel — the balances between your 351 and an AOD-equipped 302/351W are different (28.2 ounces for 351 up to 1980, 50 ounces after 1981).
That said, we’d suggest using the C-6. While it doesn’t have an overdrive gear, it is strong enough to handle your engine.
(Editor’s Note: Our post originally stated the diameter of the AOD is too small to fit the Cleveland. However, the 351W and 351C share the same bellhousing, allowing the AOD to be mated to the 351C by using the pre-1980 flexplate. We apologize for the oversight.)
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89-95 Tbirds SC made more torque than 351C (Net v Gross). C and W uses the same bellhousing M is different. Use pre 80 flexplate
We appreciate your feedback and always like the input we get on these Mailbag questions, Bowez. We have updated the story to include some of your observations. Thanks again!
Too small to it a Cleveland ???
I’m planning to run a C4 which came out of a 351 Fairlane behind my Stroked 302 Windsor ( 347 cubes ) will this Transmision be up to the job??
try 4R70W fit my 351c
Personally I’d run a AOD over a C4 cost about the same to have built and you get OD.
A 4R70W will have the exact same fitment issues as an AOD and you must get either a 3.8 or 5.0 4R70W, plus will need a controller for the 4R70W.
A built AOD should only run ~$2000 and support over 500HP, which would IMO be a better option than a 4R70W in a non EFI car. A built AOD will be mostly 4R70W internally so all you would lose is lockup
You won’t lose lock up because the beauty of the AOD is lock up works mechanically in the converter.
I’m currently running that set up without any issues. A 351C with AOD transmission. Change the flex plate to like a 88 5.0 or so, it’s 50oz. AOD bellhousing mates to 351C without issues. As long as you are not drag racing it, you’ll be fine. When you start launching it hard, that’s when issues arise.
I was told GEAR STAR Transmissions can build a Level two AOD That can bolt right up to the 351c and can work with up to 500 hp with no problems. Cost is 3995.00 Has anyone checked on this information ?
I have a 302 blueprint engine which is 50 oz. balance flexplate. Thinking of going to 351C. Will my AOD with a 2400-2700 torque converter work with this engine?