There is an ID chart in .pdf format at Hurst Click on the '05 full version. The 4 spd id's start on page 53.
It's a 4 spd. Saginaw. It looks like a mid 70's or later trans with the three holes at the bottom of the tail housing (used for a torque bracket on Vegas, Monzas). The trans was used by numerous different GM models but mostly Chevys and usually not high performance, I think from about 1968 until 1986. I don't think you can determine gear ratio by casting #'s. This site may help. http://www.dandltransmission.com/