Thats a good question,,I think its not very likly to get 80/90 in the trans,,the pressure in the auto I'm sure is greater then in the t-case wich would keep out the 80/90..On the flip i doubt it would hurt anything having atf in there..Alot of cases run atf,,all mostly chain cases but i don't know what damage if any would happen..My guess is you would just change your fluid a bit more often..
