According to
Velo-Retro: Colnago Super Timeline, the Superissimo was introduced in 1982 with new decals and chrome head lugs.
My one example does not have a stamped brake bridge. The only reason I believe mine is a 1983 is the PAT date on the RD. It could be a 1982.
The ND rear DO is stamped "USA"
P8011015 on Flickr
DS is stamped "53." Since the ST measures 56.5 ctc, it is not the frame size. Unfortunately, the frame is a bit on the small side for me as can be seen from the picture above. I prefer a 59 ST ctc.
P8011012 on Flickr