[MidOHasp]

The Tremec 3550 was a response to T-5's blowing up all the time. The 3550-II is the SAME transmission, but with 0.80 OD not 0.62. The TKO is the 3550 but w/ bigger I/O shafts and higher torque capacity, TKO-II is like 3550-II w/ bigger I/O shafts.

Not as "good" of info as on ttc website, but I think this relationship helps a person decide - it helped me.

One thing to keep in mind is that the torque numbers they give are "dry" torque numbers and would be the equivalent of putting that much torque against a set of tires that won't spin on a car that won't move.

I have heard (and made my purchase as a result of) plenty of information indicating that the 3550 can handle 500+ lb-ft and if driven nicely (not my case) could even last 50,000 miles. Maybe.