Try to process this frame using the "Colnago Frame Dating, Version VI" that was diligently compiled by Chuck Schmidt from our input and comments:
No top tube braze-ons = pre 1977
Long drop outs = pre 1976
Fork crown with COLNAGO = post 1976??
Also, the later-style Columbus decal? Perhaps a mis-match of frame and fork and/or repaint from 30+ years ago?
I am curious about the Columbus decal. I have an original-paint Mexico that I am dead certain is from 1975 with a similar Columbus decal. I know these can easily be switched, but the Columbus decal on this frame has a patina that is consistent with the rest of the paint and decals. Does anyone have a photo of a Columbus Record tubing decal on a Mexico frameset from this era? I have never seen one.
Jeff Pyzyk
Milwaukee, WI