So if you are adapting a top shift gear drive case to a G58 you are using a 3.0 adapter kit. That adapter kit should have came with a coupler and seal housing. You need to remove the seal out of the trans, put the coupler on the output shaft of the transfer case, tap the seal housing into the back of the trans over that, put your trans seal into the seal housing and then mount your tcase with the adapter.
