gas tank sending unit??

Fuel sender, fuel sending unit:
Disconnect cable release and the two rubber hoses at the gas fill assembly (loosen and raise bed slightly [see below] to remove the larger one).
Remove the three 17mm-head bolts on the passenger side bed frame.
Loosen the corresponding bolts on the driver's side, about about 2/3 of the way. Use a 16 inch 2 x 4 on a floor jack to lift up the passenger side of the bed Tighten the jack, and up tilts the bed. I used a 1/4 inch drive ratchet, with 1/4 inch socket and a #2 Phillips bit (and two hands to hold it straight). All mine loosened, but maybe because I'm in Arizona there was no rust; I replaced with 7mm head hex head screws (4mm thread x 8mm long, with a wavy washer). To line up the bed so I could get the three 17mm head bolts back in on the passenger side, the bed needed to be jacked up a little, then I could use my weight to shift the bed a little from one side to the other.