Well, about time I jumped in!
I got it off a guy in 1995 who busted his arm racing, oops :) good for me!
1992 (possibly 1991?)
18" Frame
SN / MADE IN USA Stamping - G18166 Made in USA stamping.
Seat Tube Insert/Shim - Nope
Head Tube Shape - flared/larger at top and bottom.
Rear...