I would also double the filler hose of the gas tank. I had a problem with gas smell and found the rubber hose that connects the filler tube on the outside of the truck to the metal tube feeding the tank on the inside of the cab had a loose connection. Over the years all the movement had the rubber hose almost pulled off on the low end. The hose clamp was not very tight either. When I would fill up gas would leak out around that connection into the cab.
