Oh and also, it's not true ALL new sending units are junk. Spectra makes fine products. They are located in Canada on North American soil. They make quality products including sending units, gas tanks, radiators and heater cores.
Totally agree with one caveat, the accuracy of the sending units. I believe even Spectra uses a linear wire wrap on the resistor, so with the A-body tank not having a consistent cross section there will be a little inaccuracy there.
I've wondered if they make them like that intentionally because of variances in the actual ring on the gas tank. A kinda "adjustment left to the end user" kinda thing.
Yeah I don’t think it’s really intentional. Just the result of varying thicknesses of the tanks and the lock rings. But I doubt anyone stresses out about getting them perfect since you can adjust them.