Maybe this will work. (Chevy Duty)
(1947-54) Gas Tank - Under Bed
Image not available This is a new 20.5 gallon Stainless Steel Gas Tank that is located under the bed. It replaces the the factory tank that was located in the cab. It is located behind the rear axle and requires the spare tire mount to be eliminated. (*No Free Shipping) *Note: This item may be drop shipped from the manufacturer and could take 1-2 weeks for delivery.
Part # 23-924A