i got a 1993 f150 4.9L I6, 5 spd manual. i had trrew it into reverse and gunned it and he shiffter had almost hit my knee. would this be a worn tranny mount? i would hear a clunking noise when i would shift some times, and i would feel the clunk under my feet on the floor. the motor mounts are good.

Put it on jack stands and look at the transmission mount. You have to do some checking to find the problem.