demo derby transmission failed

Extremely *stupid* conditions...

Of course you know this because you were there??? Back to the OP's question, These were not bad transmissions, what all was tore up besides the front tire?? Was the lower control arm mashed in with the axle up against the case? What noise did the tranny make when you put it in gear? Since it did work when it cooled down it really leaves alot to look at. I would start at the engine and transaxle mounts, see whats left of them. Sidecover, etc the same...

Not to mention little stuff, like bent or broken shift linkage so that it wouldn't go into the gear you thought you were selecting.

Yeah, demo derby is stupid.... if you use collectable cars or cars that could supply parts for collectables. But its the perfect fate for a Cavalier... :-p And it sure is fun! :-)

The car is in fine shape. I'm going to run it again next year if I fix/replace the tranny. No damage at all to the drive train. The car does not move in any gear 1,2,D,R except very slightly sometimes. I can hear a lot of noise which I thought was a rod knocking but now I suspect the drive chain may be slipping?

Since you have the benefit of being able to see/hear the problem I suspect that you are right. Or the converter is bouncing around on a busted pump housing...

Is the chain/gears a common failure?

No, not in my experiences.

What an simple minded statement...good gawd!! What would ever give you the idea that manufacturers would consider the habits of drivers who repeatedly crash junk cars into one another.