I do not have a mustang at the present time but my car has all mustang driveline so I hope i am not out of line posting here! I have a pro street 1960 falcon (almost a mustang) It has 94 5.0 cobra motor. When i bought this car it had the A4OD tranny in it and i had no vibration problems. Well when this trans. bit the dust my friend who builds trans. insisted we change it to a C4 and that is what i did and also put in a stall conv (motor has E cam) Well i now have a bad vibration at high RPMs. I used the same flywheel when i changed to the C4. My friend who built the tranny now wants me to get another driveshaft but i say the driveshaft was fine with the A4OD. Why would it be bad now? Can you not use the older C4 tranny with the newer 5.0 roller motor because of some balance issues that we are not aware of? I took the stall conv. out and put a stock conv. in it and it is alot better but its still bad. Any help with this problem will be greatly appreciated. Thanks, John.

 

he probly put a 28 oz flexplate on your 5.0. which puts your assembly about 284 grams out of balance...lol...at least thats what mine was when i did that on my 62 fairlane.