my old tranny used to drain into the tcase. i bought a rebuilt one from bowtie last year, and today when i checked the fluids the tranny was low and the tcase overfilled. i was told when the old one was doing this that there is only one seal, on the back of the tranny. why would my new tranny be doing the same thing? i havent checked the tranny/tcase in awhile so it mighta been that way for awhile. what could causs the seal to fail? how easy is it to replace it?