I'm positive it's pressed in there. I can't imagine ever finding someone with the integrity and skill set to completely disassemble the trans, fix the leak (and anything else that needs replaced) for a price that would make me wish I hadn't spent the money for the TKX.I think that cluster shaft is a press in fit in the front. Somewhat common to develop a leak there. Hard to get fixed. And that gear runs on needle bearings that gets tricky to work with too. Best fix is that new Tremec.
Maybe I could find someone on this site, but within 300 miles of me? I suppose weirder things have happened.