If you have a handheld meter it is easy to see what is happening with the sender. Set the selector to the lower Ohm (resistance) setting ... might be 0 to 200 ohms or something. Remove the wire from the center of the sender unit. Hold one probe to a known good ground and the other to the center post of the sender (you don't need the ignition on for this...you're just testing resistance). With those two connected, sort of rock sideways on your seat and make the gas slosh around some...just a little. Not a tidal wave. If you see the reading on your tester moving up and down (in numbers...ohm numbers, that is) rather smoothly that's a good sign. If you see any sort of erratic action (numbers going from maybe something like 20 ohms back to 0 and then bouncing back to 20 or something as the gas moves back/forth) that's a sign your sending unit may not be working as it is supposed to...or it could be a sign you're not keeping a good contact as you're holding the two probes. Sometimes that's hard to do on a hot humid evening. I have been known to get 2 clothespins to hold those firmly in place. Good luck!

~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end