raw fuel smell from gas cap

[dropanddrag71]

I have a 70 c20 and i have a raw gas smell when driving with the drivers window down, not all the time, seems to be when theres a breeze, then i smell it... zero smell inside the truck and i checked everywhere. If i bend and smell the gas cap area, it smells like gas even with the cap tight! One thing, the truck has a new exhaust and the previous owner stopped it before the axels and all the fumes dump under the truck.. I tried a new locking cap and a new regular cap... Is this just all part of the experiance with these trucks?