Can a torque converter out of a 350 Chevy work on a 396 Chevy big block?
As long as the flexplate is the same size or has additional mounting holes.
To add to this answer in depth. i changed from a 350 to a 454. the 454 had a th400 transmission and the 350 had a th350 transmission. (This was a 4x4 so we had to use the th350 transmission because it had a married transfer case)the th400 flywheel did NOT match the th350 torque converter. We installed the th400 converter and it fit perfect in the th350 transmission. I would make sure torque converter bolts to flywheel and as well fits into trasmission before attempting to install in vehicle. It is a huge pain to make the swap half way through the install.