the 53ford 1/2 ton i had the fuel tank was outside of the frame ,just as bad as being in the cab. 

You will need the 53-55 running board mounts for the drivers side. The early mounts have a sharp bend to clear the tank. The 56 mounts are curved in a larger radius. I can't tell you for certain that the early mounts will bolt to the 56 frame but as far as I know the running boards are the same so the spacing must be the same.

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

Did anyone try to install a 53-55 fuel tank in a 56 truck-- get ride of tank behind seat and like the 53-55 fuel tank and fill locations and is SAFE behind frame----- any pictures finish product---Thanks