Fuel tank sending unit

new rings are thinner so they tend to not compress the gasket as much resulting in a possible leak. The new senders are somewhat generic in the sensing unit so they may not reflect whats in the tank accurately. Grab a older Ford if no Mopar......

Empty Full Vehicle Application
73 ohms 10 ohms Most older Mopar
0 ohms 30 ohms Most pre-'65 GM
0 ohms 90 ohms Most GM 65-present
16 ohms 158 ohms Most '87-present Fords
73 ohms 8-12 ohms Most Fords before '87 and most Chrysler
240 ohms 33 ohms Use with 3262 sender
10 ohms 70 ohms Ford Bi-Metallic Gauges (pre-1987 F-Series Trucks)
15 ohms 160 ohms Ford Magnetic Gauges (1987 and later F-Series Trucks)

fill it up until it stops and then look at your gauge. It is what it is.....full is least amount of resistant so at full it should read least ~10 and empty it should read most ~73. Id run run it dry and read the resistance and then adjust the resistance value to read 70-73 on the meter with a variable resistance potentiometer (ie an old volume control) and then solder in a real 0.1% tolerance (purple band) compensation resistor. Full tank is an afterthought as you generally just fill it until the nozzle shuts off.