This one is really strange. Normally, the pump peg, multiple bottle bosses, lack of front derailleur hanger and lack of embossing would have me thinking no older than mid-1980s and no higher than mid-range. However, the presence of a 3rd set of bottle bosses and lack of paint have me wondering if the frame has been modified.

At this point, I'd be trying to identify the brand and level of tubing. I'd be checking for a logo on the outside of the fork's steeer tube, then determining the seat post size it uses.