Assuming it is the shift rod shaft seal, here's the
tech article on how to replace it. You don't need to drop the motor or tear apart the tranny.
There are some other articles in the archives. My recollection is it is a bear to get the seal out of the tranny - you'll need a hooked seal remover and some cohones to dig enough. Be careful not to score either the shifter rod or the case side or you'll be pumping out smelly tranny fluid.
Don