Quote Originally Posted by pepi View Post
265-350 SB-Chevy Internal Balance 6-1/4'' Diameter
400 Chevy External Balance 7-1/4'' Diameter look on the back side for the counterweight.

Fluiddamper does offer a 7-1/4'' 265-350 SB-Chevy Internal Balance. so it becomes important to look at the back side in order to verify the part. Diameter is a quick way to tell, counter weight confirms the part.

There is no counterweight on the stock dampner, there is however counterweight on the stock flex plate. If you desire to use a manual tranny behind a stock 400 sbc you must use a flywheel from a 454. Been there, done that.