I have a Jeep valve and grommet on my car. It works, with slight modification. The Jeep tank has a deeper flange in the hole so the grommet and valve don't seal tight. I made a plastic spacer to go between the valve and grommet to make up the difference and used a 2 part epoxy also, to kind of glue it in place so it won't leak. Also need a rubber plug to plug off the extra port. The one I got had one big port, and one small one. Downside is, it's a one shot deal but when would a person ever need to remove it again anyways?
It'll take me a bit to find the paperwork that gives the year and model Jeep I used.
The right parts might be found now. I did mine a few yea ago and never located real parts.
For reference though (from '79 parts manual) the original parts are:
Grommet p/n 4002149
Rollover valve p/n 4002252