Fuel Sender Blues

[1987 GMC Jimmy]

Much to my dismay, after siphoning but a couple gallons from my tank, the gauge still said a quarter of a tank. I know it may be the gauge, but I'm gonna get another cluster, anyways, and it behaves exactly like the Jimmy gauge, which I know for a fact it works. I see that AC Delco, Delphi, or whoever discontinued their line of sending units. I guess they thought screw everyone having tanks without fuel pumps in them, and the parts stores only carry Spectra and Dorman. I've heard Spectras are poorly made, inaccurate **** but nothing on Dorman. Should I gamble with someone's leftover OE sender from eBay, can I repair my old one, or should I bite the bullet and buy a likely poor quality aftermarket part?

 

[1987 GMC Jimmy]

Also, the sender that's in it is a two line unit. All the ones that I see for sale are three lines except for one on RockAuto, and that one says for models without air conditioning, which isn't me. Do I need to get a three way pump and plumb a return, or should I just leave it the way it is? Or again, is there a way to repair the factory sending unit?