There should be 3 pairs of bolts holding it in, one pair forward, one pair middleish and one pair rear, the fuel filler hose, and the rear light wiring which should unplug behind the rear bumper. Depending on if you live in the rust belt or not you may have to cut them off and use new bolts when you reassemble, or you may be able to just back the nut right off of them. I'm a little iffy reusing any type of load bearing fastener, new ones are cheap insurance against certain disaster if the old bolts fail with a load in the bed. Once you get the bed free you should be able to get a buddy on each corner to take it off, or if you have some kind of overhead crane/chainfall/comealong available you can run a strap around it and pick it off.