RE: 2000 mustang trans
Hi Crusin' welcome:
Sounds like you're into this.. My recommendations:
One Piece '93, drop all other year the years. Some question if all '93's are one pieces. It's accepted truth that the one piece will handle up to 3.73 gears. Also at the 3.73 level, consensus is you don't need the tail lube mod. Problem is that if you do the lube mod, you practically have to replace the rear tailshaft bushing. If you take a stock replacement, and press it in, the yoke won't fit thru. It's very hard to hone it out for a perfect snugg fit. That's why FORD doesn't sell replacement tailshaft bushings, they're all aftermarket and need to be machined to fit. Mine isn't as tight as the stock 85K mile tail shaft was. I suspect it'll leak a bit. When in doubt, your tailshaft bushing isn't a major maintenance item (and if you don't feel slop, leave it alone), and if you trash/replace it, you'll probably need the tailshaft machined for tight/low vibe clearance.
Your mileage may vary,
mark