I have had my Tremec for a few years now without any problems.
The installation is pretty simple, like the others said you need to cut the welds on the cross member but no big deal. I just took my cross member out, cut the welds and moved the supposrts all the way back and then rewelded them. When I bolted in the transmission the holes aligned, they are slots so you have a little room to play.
The shifting is notchy I guess, but Ireally like the feel of the crisp clean shifts. IMHO, a very good mod.
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fordgasm
CLICK HERE to see my 87 GT