The tailhousings are interchangeable as long as you arfe using 'non world class' (GM) transmissions. There are several S10 T5 on e-bay now. You wnat to find one with a mechanical speedo. You can buy a converter for one with an electric speedo drive, but those converters are expensive. They are referred to as 'Cable X' converters. They will cost you more than the transmission.
I found mine on Craigslist for $100. Try to find one from a V6 S-10. Be patient, they are out there.
You can download a service manual free from TTC Technologies Inc.

Good Luck-the T5 conversion is the best thing you can do for a street daily driver. I can lug my truck down to about 17-1800 in 5th gear and drop it into 3rd gear and have the RPM's be right at 3600 or so, smoothly, and be right where my HP comes in.

If at first you don't succeed,
then read the directions and try again.