Good info guys, thanks.

I was indeed fooled by the words on the cap... it says "not vented" and I saw the same gas cap listed for that year range in the
stant catalogIt seems when they say "not vented" they're distinguishing between an open vent and a low pressure relief valve.
I hooked the cap up to the air compressor just now and verified that it does vent, it just takes a few PSI before it opens.