Samllwwb - Here's a useful
T5 Identification link that gives info on the units based on the original stamped metal tag/sticker codes. It lists the applications they were originally used for as well as gear ratios, including the final OD ratio. Good information to help you verify what you are getting.
As far as the mechanical speedometer equipped T5s, according to the above linked Lugnutz info page, the S10 T5's through 1988 seemed to be mechanical and 1989 and later have the VSS electronic speedometer setup.
I would suggest you double check the speedo output on the one you intend to piurchase. If you're wanting to stick with a manual speedo cable setup you will have to modify a VSS equipped transmission or acquire an electronic sensor that converts to a manual cable drive unit (both of which folks have done in the past) to make it do you want.
