Just picked up a few more Ryobis. All are two-piece crankcases. Thought they were all going to be junkers for parts, but all except one is OK. I'll have to say that not every engine with signs of corrosion on the outside is bad on the inside, but be careful or bid down the price. It seems like most guys don't want to bother with the one-piece cases, but it looks like there are still a load of two-piece cases out there.