Trophy Classes:
A - 1908-1958
B - 1959 -1964 Full Size
C - 1965-1977 Full Size
D - 1978-1995 All except Firebird & Fiero
E - 1961-1977 Compact/Intermediate
F - 1964-1974 GTO
G - 1967-1981 Firebird/TransAm
H - 1982-1995 Firebird/TransAm
I - 1984 - 1988 Fiero
J - Commercial Stock up to 1995

 Plaques or Certificates/Popular Vote:
K - Modified/Street Rods - All Years
L - Survivor up to 1995, Pre-Registered Only
M - 1996 to Present All Pontiac and GMC