You don't have to even lift the bed off the truck, just remove the bolts on the driver's side of the truck and loosen the ones on the passenger side and tilt it up:
While I have it lifted up, I have someone shove a jackstand between the bed and frame to hold it up. Plenty of room to to get the fuel sending unit. I have replaced over a dozen fuel pumps myself. Last year the fuel pump
went out in my S10 and it took my bud and I thirty five minutes start to finish to swap it out. I had to replace my tank his past fall due to rust pin holes. I patched it with Permatex radiator/gas tank epoxy and that bought me about half a year. Ended up buying a plastic gas tank through JC Whitney so that I never have to worry about rust again. Two tips:
1. If you get another tank, you will need to get a new fuel sending unit lock ring or cam. It's the metal ring that holds the fuel sending unit in the tank. Some part stores carry them in the "help" section. If you can't find one, you will have to go the "stealership" part number is #251-24032 and the price will be around $5. When you install that new lock ring, GREASE
the living snot out of it so that it doesn't rust to pieces like to old one did. When I put my new tank in last fall, the lock ring still looked brand new and it came right out with no problems.
2. If you have a full tank of gas like I did when I had to replace my tank, you've got a problem. You need to get all that gas out. The easiest way to do it is first disconnect the fuel lines. Do yourself a BIG
favor and draw a picture and/or label the lines so that you remember where they go. Connect a short length of hose to the outlet side of the pump which will be the line closest to the cab. Run the other end of the line into a gas can(s). Then disconnect the wiring harness that goes to the fuel pump. Take a jumper wire and connect one end to the positive terminal on your battery and touch the other end to one of the leads in the plug (there are two) on the fuel pump and it will pump all the gas out. It goes lots quicker than you think it would. Only took me about three minutes to pump out nineteen gallons of gas. HTH's