Ron, I dismantled a '58 235 that did have the fiddly little lock plates on the flywheel bolts, but it also had a 6V flywheel on it, so someone had messed with it previously. The 1929-1957 parts manual shows the flywheel bolt lock plates listed for all 6 cylinders, so it appears that GM used them at least thru 1957 and I assume on into 58 and 59.
Last edited by klhansen; 12/06/2025 6:39 PM. Reason: fat fingers
