The primary damage will occure in the transmission due to windup.
It is very hard on the clutch.
The engine couldn't care less.
Tractor transmissions are tough as long as they are moving....the reverse gear set on most transmissions including road vehicles is the weakest gear set in the box.
VW's ...the old bug and early Rabbits had a problem with staying together when people would accelerate in reverse hard.
Porsche trans' are similar. The gear set teeth are usually straight, tiny, and single tooth loadings occure due to the design....loading like this is not recommeded.
Cold engine starts have far longer zero oil pressure time than killing the engine by stallling...in fact ...stalling the engine shuts it off quicker than turning the key to Off.
Like I said...engine couldn't care less.
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