What specifically are you trying to determine?
Identification is by the metal tag or by the paper bar coded tag on the top cover. None of the numbers cast into the housing will be of use. Should be something like 1352-xxx ...
If it is really a '91 S-10, then it would be NWC and have an electric speed sender. If you want to know the gear ratios, put it into gear and count the rotations...
