I had the same problem. I ended up cutting a good sending unit off a factory 5/16 unit and attaching it to a repro 3/8 pickup tube. I attached the sending unit to the pickup tube with 2 small hose clamps after trimming the side of the clamps a bit to slide thru the 2 small slots in the sending unit, and connected the factory style wire to the strap wire on the repro. Works now.