Are 383 and 400 flex plates and converters interchangeable

[Tony292]

So I have a 71 with 383/727 that should have the cast crank and spun a bearing. In the junkyard is a 77 400 but with a manual trans. Can I just use my 383 flexplate and converter or will it be out of balance?

[712edf]

If your sure its cast crank then it may work. Do both motors still have the balancers? If they're the same then Yes.

Bucky

[marklein]

No. 383 internally balanced no weight, 400 externally balanced with a weighted converter . for the most part, there were only 4 flex plates for all engines, excluding hemi and industrial, small and large with 2 different bolt patterns for the crank. I think you can buy a weighted flex plate so you can use a non weighted converter, check into it.