1952-59 Ford Gas cap??

Stupid question but what gas cap are y’all using on 56 mercury tank?
I’ve tried 3 so far to no avail. Seems the caps I’ve gotten aren’t deep enough

 

Mine was in the car 11 years ago when I bought my car. The opening in your tank looks the same as my 56 Ford. My cap has no markings but you ca see the depth of the bends to make it secure and tight. I would think CG, Carpenter, Concours, Larry Thunderbird, Prestige Thunderbird or even Mac’s would have them.

 

You need a Stant G22 gas cap. It's a deep throat, non vented cap. I have one on my '55 Ford tank and on the bottom of my box it says it fits '53-'58 Merc (exc station wagon). Here's one on Ebay......
https://www.ebay.com/itm/2351152103...NweRHWTY-i1adXZXdkzyeL0TPh-y7VAEaAjk8EALw_wcB

 

Or it might be this one. https://www.ebay.com/itm/2661030441...y05q6y4aLXoydY8LFDar_fA4TyrtyaWV3pAQGezc46B28

 

Update the G22 cap is correct. Thank you all