Okay, so I slimed the area underneath the big spacer with some sealant and tightened the nut down...should work. Then after I got the driveshaft back on (after having to remove it already today since I thought I was done last week, thanks guys for catching me and telling me about the sealant), I remembered that I hadn't staked the nut
. Off came the driveshaft for the third time this project
Also the transmission is not getting overfilled by the tcase, so here's hoping I found the leak!