I say it again. Unless you just can't stand a slushbox, the lockup KM148 is very hard to beat as the best match for a turbo motor, whether it's a 2.6 or 2.4. The turbo greatly benefits from the loose stall in the torque converter (22-2400 rpms) so the boost builds almost instantly coming off the line, with no boost threshold problems. The turbo also has plenty of torque to cruise with the .70 o/d ratio without constant downshifting. It's also very strong, with a conservative torque capability of 300ftlbs (it's torque that eats trannies, not hp). My 2.6 non i/c raider was an absolute joy to drive on and off road. With 4.625 gears, o/d cruise at 70-75 was about 3k rpms. With a .8 o/d that will be about 3425, a 14% increase. The power application to the road or rocks is superb. Expect about 8-10% slip at cruise without the lockup. I also drove this motor with a 5spd, in a d50 with 3.909 gears. The d50 was a lot lighter, and higher geared. I could not break the rears loose in it, either, with 265/75-15's (31-10.50's on the raider).

The raider was a lot quicker off the line and thru the street drags, easily beating 5.0 foxbody mustangs red light to red light. The d50 didn't stand a chance, getting pulled by a couple of car lengths easy, often more, since the 60' was so poor. I could brake launch the raider and pull a front wheel off the ground. You could also "bounce" a front wheel up onto an obstacle offroad with a good jab at the gas in lorange.

I will concede that it takes a lot more skill to drive offroad effectively with a 5 spd, but I don't count that as an advantage.