This is a quote from the notes section on the S/N page of vintage-trek:
Some early and mid 80s bottom brackets were marked with 58TSI or 60TSI. In the early 1980s Tim S. Issac designed new lugs and and a new bottom bracket shell for Trek. The new bottom bracket shell is typically marked with 58TSI (or more rarely, 60TSI). This designation is not part of the serial number but is a model number of the shell. The TSI are Tim's initials. The 58 or 60 refer to the angle between the seattube and the downtube.
So maybe 032197, an '82 Trek 720 in 22.5"?
The rear dropouts look like the long Campagnolo 1010 available on this model, and the under chainstay cable routing looks the same. Hard to tell, but looks like the older style seat cluster treatment as well.