1994 Chevy Truck TRANS SLIPS IN REVERSE

The auto trans works and shifts great in all forward gears, but when you put it in reverse it slips and doesn't want to move. If you rev the engine to a high rpm it will slam hard into reverse and the truck will move until you let the rpms drop off and then it will slip again. The ATF is at the right level on the stick. I don't see any leaks. The ATF is slightly brown, but no bad smell.

Is there any known problems with this trans. With slipping in Reverse or any hope of repair at a reasonable cost?

thanks, JL