MS6 fuel gauge not reading correctly

I bought a new to me MS6 and I recently ran out of gas with just over a quarter of a tank. I filled up and the gauge was almost 1/4 tank over the full mark.

I pulled the fuel pump unit today and tested the float by pulling the fuel pump relay and then connecting the harness to the top and manually raising and lowering the float. When the float was all the way down the gauge read exactly where it was when I ran out of gas. Just over a quarter tank. When I lifted the float all the way to the top it only read full and not over full. This lead me to believe that I needed a new bottom part (float). As I was looking online at the schematics I realized that both sides of the tank have a sending unit and a float.

My question is do these work together? Do both units need to be replaced? Is it possible the passenger side sending unit is the only one damaged?

Does anyone have any input, advice, or suggestions? Thanks in advance.

 

Multiple sending units would be averaged most likely. The standard gas gauge actually packed full of logic to balance out the signals constantly going up and down as gas sloshes, etc. I'd test them individually and compare to a good/new unit.