Here is a NOS comet Gas cap on ebay........cheap!! Looks like it fits the big bumpered Comet: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4506266557&category=34204
I didn't know the gas caps were different from big/small bumpered cars Of course I've never seen a true Comet cap in person. Seen plenty of Mavericks but my Comet has a painted black circle on it I also see a Maverick one is going for almost 60 bucks..... how crazy. I know they are rare but still.
I was the "winner" of an E bay cap like that. Not sure if it fits my '72 Comet or not. '75 and later cars have a smaller gas filler opening to allow use of unleaded only,so the caps must be different. The real hi dollar caps are the early ,'60-'63 Comet caps with Mercury Man on them.They go for over $100 sometimes. Insane.