Schwinn used the "old style" date coded serial numbers through late 1984 (e.g. D8435, which would translate to the 35th frame built in April, 1984). Sometime between 1983 and September, 1984, the serial number was moved from the left rear dropout to the bottom of the BB shell. Then, sometime between September, 1984 and April, 1985, they switched to the long "self-describing" serial numbers (e.g. 520AD8584, which translates to a 52cm seat tube frame using a fork with the short production steerer tube, 84th frame built during April, 1985).

It looks like your bike has been repainted, and the paint has filled in the old style date coded serial number on the left rear dropout. To find out what the serial number is, you'll have to carefully remove the paint around the stamped serial number on the left rear dropout using an Exacto knife or similar. It's definitely an early eighties Paramount. Once you get the serial number, we can tell you what tube set was used (most likely Columbus SLX or SL/SP mix).