350 efi to 396 bbc swap, same flexplate?

[Brando Marlin]

I'm going to swap out the 350 efi for the 396 bbc can I use the flex plate off of the 350? Smog is not an issue the truck is reged as a diesel.

 

[Bextreme04]

I'm going to swap out the 350 efi for the 396 bbc can I use the flex plate off of the 350? Smog is not an issue the truck is reged as a diesel.

Is the 350 a 1-piece or 2-piece rear main seal? An original 396 would have been internally balanced from the factory and should have a neutral balanced flexplate. A 1-piece rear main 350 is internally balanced but has a slightly counterbalanced flexplate.

So if you have a stock flexplate from a 1957-85, it will work fine on a stock internally balanced 396. An 86-later 350 flexplate will not.

 

[Brando Marlin]

Thanks for the response. The 396 is a 1966 2 bolt main and the 350 tbi is the 2-piece rear main seal. I ca purchase a flexplat but im not sure how many teath or splines it should have. Also the truck is regged as a diesel so i'm still trying to deside if i should put the 6.2 detroit or the 396. This is the thing thats holding up the project. Gasser or diesel?