[Cobra75]

Rob,
How much do you want to spend?
T5Z-$1100, 3550=$1560, TKO=$1580

I have a TKO in the Shelby (434 RWTQ) and have had it since '98 with no problems. Shifts are notchier than the T5Z I have in my 302 Mustang (276 RWTQ)

I would hope that the 3550 & TKOs are going to sell cheaper now since the new T500 & 600s are out, and you might find a bargain.

The 3550 & TKOs have the same exterior dimensions, but the input & output shafts are different. The TKO @425 lbs-ft, is the stronger rated box, but requires a 26 spline clutch disk and 31 spline yoke. The 3550 rated @350 lbs-ft has a 10 spline input and 28 spline output (same as the T5) The 3550/TKO are about 0.62" shorter than the T5.

There are also Road Race versions of the 3550 (@375 lbs-ft) and TKO (@475 lbs-ft). These have different 1st and reverse gear ratios but they are even more $$.

If you stick with a T5Z (330 lbs-ft), you won't have to change your yoke and driveshaft.

If you go with the 3550 or TKO, you'll have to change the bellhousing. I would get the FRPP steel bellhousing M6372-C ($285 list). This includes the block plate and fasteners and uses the Mustang clutch cable. This BH will also fit the T5Z.

Personally, I stick with your old T5 until it blows up.