Well my tranny sounded like metal on metal in 1st&2nd, poped out of 5th with 245k's on a N/T tranny, pulled her apart and bingo the inputshaft and couple of other bearings wear worn, replaced those, seals and a 5th-rev synco and she's smooth as can be with 269k's and turbo @ 15psi, just shift proper and maintain them as said.
I drive my car hard, always have, but you gotta shift right with these cars!