I converted from a switch to a sender yesterday. My truck is a six cylinder so the sensor fits without needing pipe fittings to extend it out. I used a Borg Warner sensor S334, $10 at O'Reilly's. Unfortunately the 20 ohm resistor is in the engine wiring harness on my '88, not on the dash printed circuit board. I didn't want to tear up the wiring harness to get at it, so ran a new wire from the fat harness up on the firewall to the sender. The wire to the sender is white with a red stripe. There are two of those in the fat harness. I had to nick the insulation on both of those to find out which one that measures 20 ohms to ground. Then I just cut that wire, soldered and heat-shrinked a new wire to it, ran it down to the sensor, and soldered/heat-shrinked the sender connector to it. Real gauge now.

 

Some reason it shot back up to the m on normal, who knows but im goona buy a mechanical gauge anyway