[72stangG]

Im looking for all options on a transmission for a 351c in a 72 Grande. I may need a new one. This one slips bad. But sounds ok, no grinding hard to go into gear, jerking etc, Just wont go and when it does it picks up very slowly. Any help or advice appreciated.

[Jay H 237]

The stock one you have should be a FMX. Your bands may just be out of adjustment and allowing the slipping. If you keep driving it like that it just wears the bands quicker and creates heat too, the main enemy of an automatic. Readjustment of the bands and a fluid and filter change may be all it needs.

If need be you can just have the tranny rebuilt too. The FMX is a good tranny if you're planning on keeping the motor stock or near stock.


If you're not interested in originality and planning on beefing the motor up greatly then a built C4 or a C6 may be better. Even an AOD may be an option.

[72stangG]

I dont have the car with me, I was trying to drive it back. Which I decided against when I seen how bad it slipped. It did get hot, I could feel it through the floor. Its without the carpet and what not.

All I can do is change the filter and fluid where its at. I know the fluid was black. Once I do get it back I can take it to a shop and have them check or adjust the bands then.. I just need to get it back home and its about 2hrs away.

Do you think its worth trying a new filter and fluid? If it feels good then go for it and have the bands checked later??

I know the car sits often. The engine sounds great though and has low miles. Thanks for any more help or advice!..

[Jay H 237]

Black fluid is not good. The tranny could have burnt up (happened on my high mileage Caprice) and may need a total rebuild.

With that said a fluid change can't hurt but just dropping the pan will only replace about 1/3 of the total fluid. The torque converter and valve body will still have the old fluid. I'm not confident to drive a car in that condition for 2 hours. If it was a half hour or less then I'd give it a shot after changing some of the fluid and seeing how it shifts.

[72stangG]

I would replace the valve body but its something about being marked with a certain color and I need to know that...? I called one place on that, maybe I can get it elsewhere if someone knows what I need.

Ive been looking around for another transmission.. Ill see what happens tomorrow when I go there though. Maybe I can get a valve body in time to have that changed too and see what happens. Thanks for the help