Seat & Fuel Filler Caps
That seat , along with the rest of your truck , loks mighty fine .
You have the WRONG gas cap ! there is NO relief valve in it ~ ALL Chevrolet trucks use the same fuel cap from 1937 ~ 1970 , look it up in the STANT catalog @ you FLAPS , it's a nice smooth cover thing with stainless steel polished instead of the original steel paint to match one .
It is vented , no valve .