[Tom]

Trying to figure out what this is for.
NOS sheets list it as:
6429286
Gauge
73-75 AD- AF- AG 2 B.C./A.C. exc S.W.AD- AF- AG 4 B.C. exc. S.W.77-77 AD 29-37 AG
I think AF=Firebird and AG=Grand Prix.What is the AD for?
Any help appreciated.

Thanks,Tom