Fuel Tank Sending Unit Problems

Hey All. I've changed the spectra fuel tank sending unit in my '73 Dart 4-door slant six three times now, and none of them read right. Can anyone please tell me where I can to find a reliable one? Thanks.
Shawn

I had to bend the float arm on my aftermarket sending unit to get the gauge to read accurately. Before I mounted the sending unit, I hooked up a ground wire with alligator clips to complete the ground circuit, I had a buddy read the gauge while I moved the float from empty to full. As I remember, I had to bend the float rod pretty significantly to get the correct readings. It' worked like a charm, and my gauge has been very accurate ever since.

The after market rubber gaskets are not as good as the factory ones, so I ordered a good repopped on from Detroit Gaskets. I forget what their shop is called, but they advertise on here. It works great. No leaks.