I don't claim to be an expert on T-5's, just a guy that did some research and installed one in my truck. T-5's were used in AMC's, Nisson's,GM's, Ford's,Isuzu's. These were Non-World-class transmissions and were equal with exception of the gear ratios. In the Camaro's and Mustang's a World Class beefed up close-ratio version was offered with a variety of ratios. However, the WC T5's had the shift tower to the rear and would have had the shifter popping up in the middle of the seat of your truck.
The primary reason the S10 T5 is so popular relates to the forward position of the shift tower. It is oriented about 6" to the rear of the stock sm420 shifter location. The popular 1st gear and overdrive ratios are from the V-6 boxes while the 4 cylinder boxes have a higher number 1st gear and higher number overdrive. The key is to mate up your T-5 ratios with your differential R&P numbers and toss in your tire diameter. I personally wanted a setup that was inexpensive, lighter than the 175 pound sm420 (T5-75 pounds), fit with little modification would let me utilize my 235's low end/low rev torque and cruise at highway speeds with good mileage as a premium.
As for durability, I've never heard of anyone tearing up a T5 behind a stock 235. Not that it isn't possible....
