here is a write up I did.check your rearleaf spring shackles and hangers.....
In many cases Removing the Bed Helps in the aiding of repairs. ie. Fuel pump replacement, hanger and shackle replacement, etc
1)the fuel cap filler is held on with 3 bolts 7mm?
2)there is an electrical disconnect at the bumper for the taillights.
3)The bed is held on with 6 torx 55 bolts. 2 of the bolts closest to the cab are longer than the other 4. I recommend buying 2 torx 55 sockets in case one breaks
4 or 5 of the bolts can be accessed from underneath and should be hit with a rust penetrator
I recommend at least one of the following, impact wrench, 1/2 ratchet with a pipe or a 1/2 breaker bar. it takes some muscle to remove the bolts.
4)The bed can be slid down for a fuel pump replacement or removed my 2 Men. a cherry picker.
5) In the event you are removing the bed for a fuel pump replacement. MAKE SURE YOU DISCONNECT THE NEG BATTERY TERMINAL.
6) You should change your fuel filter hile the bed is off. tool required or equivalent 5/16 FF performance tool W83130
7) I replaced my bolts with regular hex bolts. Ford wanted $16 a bolt. I ordered my online for less than $3 each. the 2 cloest to the cab are 12m x 1.75 x 120mm and the other 4 are 12m x 1.75 x 100mm
8) I changed the rear hangers and shackles on my rear leaf springs. I used Dorman 722-010 and 722-001. all 4 pieces were less than $100. They come in a kit with everything you need, bolts etc. I used a grinder to grind the heads of the bolts off. this only took about 10 minutes a hanger. I had a dewault grinder and bought 2 metal grinding wheels at the home depot. I only used 1 they were about $3. I had a hard time getting the bushing out of the eye of the spring. I finally decided to use my drill and a good 1/4 bit. I drilled the rubber out that was in the middle of the bushing. the rest just slide out. I greased up the new bushing and temporarily put the bolt in and hammered it in the eye. You don't want to torque the bolts that attach the spring to the shackle until the truck is on the ground.