Bench testing two cheap eBay fuel sending units

Due to the tanks shape, the swing of the float lever is irrelevant to the reading on the gauge to gallons in the tank.
Product Review: A100 Fuel Sender For 67 Dart

Fuel Gauge Sending Units compared

Close as you will come to getting an OEM fuel sender..

The only way to test the senders is to put them in the tank and fill the tank 1 gallon at a time.

The bottom of the tank is rectangular but with a slope on 2/3s of it. Then the top half has the spair tire cut out

Then there is the guages itsself . On one of my charts you can see the restance needed to make the guage read E 1/4 1/2 F and it is curved. And it's curve closely matches the later mopar sender, but the other senders I tested were much more linear.

Good luck to you.

BTW... If anyone has an 18 gallon Dart tank they want to part with, (can have a few holes.) I will cut an access hole in the top And video and measure the inches up from the bottom per gallon.