I gave up trying to get a decent aftermarket job (4 units, 2 vendors, refunds given, no return of part wanted) and shipped my 5/16" sender out to these guys:
http://www.tristarrradiator.com/The problems with the aftermarket ones seem to all be with the rheostats, and all of them were of slightly different construction. One would show full right after fill up, then drop almost immediately to empty (before I got out of the gas station), one showed empty with a half tank left in it, one would only show a little over half a tank when full and the other seemed to move the needle to a random location and go from there every time you started the car. I'll swap out the showing empty at a half tank one for the rebuilt job when I get it.
I should note that none of these were Spectra. 2 OER and 2 unbranded from Vans Auto.
I'm having it converted to 3/8" with a 5/16" return. I have heard good reports about this place, and the guy is knowledgeable and responsive. I'm expecting it back for installation this weekend. I'll post back here.
The sender was working fine, I just needed a 3/8" pickup to feed my new setup.
I'll post to this thread once I have the reworked one installed.