This will give you an idea to work it out roughly.
A. 1977 to 1978 - No markings, may have had a Tuf Neck sticker on, Square corner.
B. 1979/80 - Tuf-Neck Patent Pending engraved on the cap, Square corner.
C. 1980 - Tuf Neck 2000, Rounded front and back.
D. 1981 - Introduction of the Tiger Head and Tuf Neck USA stamp on the cap.
E. 1981 - Rounded corners with Tiger Head and Tuf-Neck USA stamp (I think was done to prevent further knee injuries).
F. 1982/3 - Rounded corners and Potts Mod bolt. Tiger Head and Tuf-Neck USA stamp on the cap.
G. 1984/5 - Tuf Neck ACE model - Rounded corners and Potts Mod bolt. The stem was made shorter for Freestyle and flatland by adding a cut out in the cap. Tiger Head and Tuf-Neck USA stamp on the cap.
H and I. 1985 to 1987 I believe. Same as previous models, Tiger Head and Tuf-Neck USA silk screened on the cap. Not sure for what purpose though.
