I am building a 555 for my shadow. I am replacing all the bearings seals and fork pads. The transmission originally broke spider gears and put some metal through the trans. After disassembling the transmission it turns out the differential was changed at one time because it does not have 4 spider but rather 2 like the other transmissions. The differential cover was also welded in a spot which turns out it spit the pin at one time. I have a good 555 differential out if another parts transmission. I was going to swap the ring gears so they are a matching set but the ring gear from my parts trans looks better ( less wear and no blueing, the original has a little ).. Should I use the original ring gear which is a matching set with the pinion or should I use the parts ring gear which looks to have less wear but is not a matching set? I am just curious has anyone ever broken a pinion or ring gear? Any advice would be appreciated.

Thanks,
Justin