This crank Shaft Turning Socket by Proform is made from non-marring aluminum with an 1610 inside diameter and fits chevy 1965-1992 chevrolet all big block models When your harmonic balancer is off, place this socket over the end of the crankshaft with a 316 keyway Turning your crankshaft can be done with socket and a 12 breaker bar or drive ratchet