Yep - could very well be a fuel pump.  In that case, I'd first get a fuel
pressure gauge on it, and see what the pressure is in the rail when you try
cranking it.  Again - you want to make sure of the problem before tearing
into it...  if the pressure checked out good (between 45 and 50psi), I'd be
looking elsewhere (possibly to water contamination, in which case I'd drain
the tank as discussed before - assuming the engine fired with starting
fluid)

As for replacing the pump, you have two options - either drop the tank or
remove the bed.  At 133K, those bed bolts are probably pretty rusty (or else
that's really the easier method - just a few bolts, disconnect a couple of
wiring harnesses, unbolt the filler neck, and four guys can easily lift it
off and set it down).  If you opt to drop the tank, get as much fuel out of
it as you can, and use a floor jack with a piece of plywood on it to support
the tank.  Remove the two straps, lower it slightly, disconnect the lines
and electrical from the top, and pull it out.

From there, you'll have to remove the lock ring (FSM shows a special spanner
wrench, but you can tap it off with a screwdriver and a hammer - rotate it
counter-clockwise), then pull the whole fuel pump module out.  This is
serviced as an assembly, so you're looking around the $300 range for a
replacement.  Replacement is pretty simple (make sure to get a new gasket) -
put it back in, put the lock ring back on, tap it snug, and put the tank
back up (or the bed back on).

Now, if I were doing this myself, I'd probably see what could be done about
removing the fuel pump from that module, bypassing it with some hoses, and
installing an external pump right on the frame rail.  Not having actually
done this, I can't give you any specifics, but I always hated the fact that
#1 the pump is inside the tank, and #2 it's not replaceable separately.