Jim Lee,

Here are some thoughts. There was a thread recently about reproduction fuel tanks and the strange thread configuration of that bottom bung. Trucks of your years had the tank line exit the bottom. LMC might be under some legal constraints to make sure they inform the customers that this is a 'drain only' to comply with modern fuel tank standards.

To modify your sending unit with a piece of suction tube wouldn't be tough. My thought would be to research this a tad more, verify the pipe size and/or thread configuration of that bottom hole, and if all is well, install a small shut off valve and nipple, and use the bottom hole as a fuel supply line. I think it came from Detroit this way.

Stuart