Fuel Sending Unit Help?

[HenryBlue]

Hi everybody, first post here. 
Recently bought a 1990 Geo Tracker with 97K miles. The guy I bought it from put in a new fuel tank and pump, but did not install a sending unit. I can’t find one new anywhere. 

I’m sure there are others on here that have had issues finding OEM sending units. 

However, I did find a “universal” one that’s adjustable for depth, and that reads empty at 240 Ohms, and reads full at 33 Ohms. I know from other posts here that Gen 1 sending units typically read around 120 empty, and 3 Ohms full. 

I know next to nothing about sending units. My experience is with the mechanical, not electrical. 

Will this “universal” unit work?!

https://www.oreillyauto.com/detail/b/aut...unit&pos=3

Please help. 

the sending (fuel level) unit is only a variable resistor. vary simple and crude,  1920's year technology, for sure.
fitting the hole in the tank and not leaking is the big issue here,  

seen here.

http://www.fixkick.com/sensors/fuel-gauge-tests.html


full is 3 ohms,
you can test the gauge before putting it in,  connected.

The fitment can vary by year and if 2door or 4doors, car.  (tank sizes are not the same on 4door)

So if the OEM/Sidekick part shows full at 3 ohms, and the universal one shows full at 33 ohms, would the universal unit even show the tank as “full” when the tank is actually full? Or would it just burn out the gauge? I’m guessing the gauge itself is calibrated to read 3 ohms as “full”, so 33 ohms would read as less than full?

Again, I know almost nothing about electronics/electrical components.