HRL and some other fabricators will probably vote to impeach me from the forum for this post, but I did a farmer fix on my '57 GMC in 1998 when I installed a mid 80s Mazda B2200 pickup gas tank under the bed behind the rear axle.
Of course the Mazda tank's sending unit didn't match the GM 0 ohms empty, 30 ohms full gauge.
To solve this problem I removed the electrical connection (green circle) from the GMC mounting flange and then cut the pickup tube in two places (red lines) leaving me with the electrics from the GMC. I removed all the electrical bits from the Mazda sending unit leaving just the flange, fuel tube and sock. I used two small screw-type hose clamps (purple) to attach the GMC electric and float assembly to the middle of the Mazda fuel tube and ran the electrical connection through the Mazda mounting flange. The GMC tank was taller than the Mazda tank (needed more movement of the float from full to empty) so I partially straightened out the bends (marked in blue) on the float arm to allow full movement at the GMC float within the Mazda tank.
The tank and sending unit worked fine for 13+ years until some idiot T-boned the truck. In later life I have come to realize that there were two classes I really should have taken in high school, welding and typing.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
