Borrow or buy a pair of drive-on ramps, pull the back tires up on them, go to town with the t-case still in place. Far easier than chasing it around on the bench to get some of the snap and lock rings off, plus the trans acts like another set of hands to hold stuff in place for you. Super easy to do if you can sit up under the rig. I've done them both ways, much prefer under the rig.