[bigblockv6]

I know in my reading that the 478 gas requires a balanced flywheel. Does anyone know if the 478 toroflow does as well?

Thanks![/QUOTE]

A shop that I worked at did a conversion like the one you're talking about. Basically started by someone else giving up on the project. My boss told me he took over the conversion in the early 70's, the ToroFlow was replaced with a brand new 401M in a School bus. When he received it there was the ToroFlow flywheel attached to the 401M and the engine could not run above idle so he had to get the correct flywheel for the 401M. So yes there is balancing on the Diesel version flywheel, Does your 401M have the 6 bolt pattern crank flange or 8 bolt pattern? If you have the 6 bolt pattern the 305 flywheel will work. When I did my 478M conversion I had a custom flywheel built from Tilton Engineering, the basically made me a zero balance flywheel so when the bottom end was balanced considerable weight was added to the flywheel.