I just got off the phone with the parts department at a local Chrysler dealer. I think I would have had more luck talking with someone at Pet-Smart.
Anyway, the cap I bought several years ago was for a 2006 Jeep SRT-8 because it had a green Viton O-ring that works and doesn't leak like the Gen III caps.
If you are fussy, use the cap you have and find a Viton O-ring for it as that will work too. It doesn't have to be green, just Viton.
The black OEM rings dried out and shrank.
The Viton O-Ring won't do that.