I think I remember looking and they engine block wheels are not interchangable. Buying poor condition engines on ebay is one way to get used engine blocks cheap. I found that engines in poor condition - missing roof, smoke stacks, bumper switches, ususally have decent blocks. Maybe they don't get used much after the parts fall off

I've had engines in good condition with engine blocks that needed to be completely rebuilt - new springs, pickups, gease removed and relubed and the wheels sanded down to make good contact with the track.