I haven't done this yet, so I'm talking out of school, but I have read a ton. As I bought a S-10 and stripped it down and put an old ford cab on it and going to run 350 with t-5. The T-5's are cheap enough used, but true, is a pig in the poke, may be noisy/broken, etc, I see them from $100 and up. BEWARE: if you get something from '93, it will have small block ford bellhousing pattern. You'll have to use metric bolts to bolt a bellhousing to some of them (if not all unsure, I know mine is, it's a 93).
The spacer referred to is not to bolt trans to engine or bellhousing, it's because the input shaft is somewhere around an inch too long (I'm told) for trans to mount flush. so, either you've got to use a spacer or remove an inch or so off input shaft somehow. And, yes, every easy to get into one with electronic speedo tailshaft, don't know if they're interchangeable with eearlier tailshafts and able to run standard speedo (gear driven).
