1973 Duster
Fez440,
Sorry it took so long, but this is what I got.
The companies name is Roadster Shop and their internet address is
www.Roadstershop.com That being said I looked on their site and could not find anything about the gas cap.
The part number is MHD-0007 and I think it is 2.5 inches. Not sure my car is at the paint shop. the part was 200.00 hope that helps.
Call them at 847-949-7637