I have a 55 235 in the shop right now that had a slight knock on acceleration. I removed the pan and tapped the rod caps with a dead blow. Numbers 3 and 5 moved so I removed the caps and the bearings were standard bearings. The crank was stamped R & M .020. Took the rest of the rod caps off and they were all marked .020. The crankshaft wear on numbers 3 and 5 I believe has ruined this crankshaft. Maybe a little plasti-gauge might have prevented this from being run like this. But there is also a few other things that were done wrong on the overhaul also.

51 GMC 100 with 59 chevy 261 under the hood.
3 on the floor with 3.42 gear.