I have a late 80s Serotta and in addition to putting the serial number on the bottom bracket shell, Serotta stamped the serial number on the fork/steerer tube. Of course this only works if you've got the orginal fork. Serotta built with a mix of tubes, has used True Temper in the past my bike is Columbus SL. I know that Serotta used Hayden Lugs (concorde?). is there a Serotta "S" in either the fork crown, or on the brake bridge? that would be one way of identifying the bike as a Serotta.
Marty Eison
Dallas, Texas