I improved the "gas smell" by extending the vent tube slightly out the bottom of the gas tank. This puts the bottom of the vent below the cab sheet metal. First I took a bronze firearm bore brush to clean the inside of the vent tube at the bottom. Then I took a one inch length of 1/4 inch brake line, beveled one end slightly and epoxied it into the vent.

I had disassembled the vent apparatus and studied the design. There is no way that the cork ring is going to seal the vent holes completely in the event of gas sloshing up against the holes. So it is inevitable that gas will drip from the vent and when you are driving fumes are going to blow into the cab environs. This must be why GM abandoned the design after one year and in 1938 returned to the gas filler outside of the cab.

1937 Chevy 1/2 ton
1942 Chevy 1/2 ton
1947 Diamond T Model 509
1951 Chevy 1/2 ton
1950 Chevy COE Model 5700 ~ "Barney" ~ And more pix