I'm having some trouble with my rod bearings in what is suppose to be a MMR 5.0 stroker motor but I'm not sure it is. Are the rod bearings bigger on an oem crank and smaller on a stroker crank? The bearings I ordered are for a stroker crank but are much smaller than what came out of the engine originally. I'm the first person to go into this engine and just need to clear this up.