There are two different gas caps for the A-22...The supplier for the California plant used a three tang or nubs around filler neck to secure the cap, the cap had three spiral slots with a quarter turn to install it, and I believe that most other plants used an internal thread in the filler neck so of coarse the cap would have external threads....For my California A-22 I found an aftermarket "NEVA-LOST" gas cap that fit the three tangs, once installed the top of the cap flips to open...I don't have an extra of either type but hope this may help.