[mustangracer91]

just my 2cents, but the 8.8 if you can weld/have someone do it, 9inch if you don't...depends on what motor you're running too. If you're a Honduh racer and do crazy clutch dumps from every stop light, I'd say the 9 is cheap insurance...or if you're running a 400 hp+ small block or a big block...I've RACED 8.8's with 400hp + nitrous on 150k+ mile stock rear 8.8's and never blew one despite me actually trying to (so I'd have an excuse to change my gears). 8.8's aren't bullet proof, but they're pretty good. Also, your t-bird rears pre '89 will work, however they are WIDER, but most of them do come with rear disks as well...just 4lug, so you'd have to swap rotors...simple axle swap and you're done if you want 5lug...