I bought me a PMGR starter from a guy that is supposed to be a stock replacement for a later model 454. Put it on a truck today and checked out the alignment. The fit was good without shims. I took all the spark plugs out and turned the engine over for a few seconds. Everything sounded good, looked like I was in business. Put all the spark plugs back in and the first time the engine hit compression the starter make a crunch and just spun freely. I took the starter back off and took it apart. Inside it uses a planetary gear set. The outer ring gear is plastic, and now is void of teeth. Does anyone know if this gear is supposed to be plastic? I got a heck of a deal on the starter but now it looks to be a cheap rebuild instead of a GM original. I can't see how plastic would ever stand up to the stress, and it didn't. What I need to figure out is whether this unit is inferior to GM's orignals or if GM goofed.