I've replaced my pump twice in recent memory on my 98 2wd. Once with the bed off last January, and then again earlier this year using the bed tilt method. I don't drive it often and left the fuel level low enough for the pump to seize. Replaced the pump anyway, but a soft shock to the pump freed it up.
My replies to your post...
1. No lock ring; just six small screws and an o-ring.
2. I didn't remove the FSU, but did clean up the contacts. I want to say it just snaps or clips on to the plastic piece that holds the fuel pump. Not sure if the pump blocks access to the clips, though...
3. Bed tilt method is...interesting. I didn't enjoy doing it. I tilted it sideways, and not to the rear like dumptruck. I used some 4x4 blocks to prop it up between the bed support beams and the frame, and also kept the two driver's side bed bolts loosely in the frame (rear-most bolt removed because it's not inline with the side bolts) mainly as a pivot point, but also out of fear of the whole bed sliding off or something dumb. Also:
- get a friend or a cherry picker to help; I definitely don't recommended doing it solo with a floor jack or anything like that. It's heavy and awkward to grip, not to mention the only decent place to lift by hand is the wheel well...which means you'll most likely be blocking the space where your helper needs to shove blocks into.
- tuck a towel or blanket between the bed and cab to not scratch things.
- disconnect the license plate and tail light harnesses
- I think the bumper needs to be removed...mine was already off but I presume it would be in the way (i.e., scraping the tail of the bedside)
- remove the 3 screws holding the filler neck to the bed, and push the filler neck away so it doesn't snag anything when tilting.
- There's a fuel temp sensor inside the tank, and its wire runs to the assembly. Don't try to pull the assembly out before disconnecting, of course. On my truck, that wire also had some extremely brittle plastic wire loom on it. I removed what I could and fished out the pieces.
4. When I had the bed off to do an axle swap, I wanted to replace the "biscuits" and the bed bolts. I think all those parts were ridiculously overpriced for what they were, so I found some salvageable hardware off a junkyard truck, and bought a pack of Energy Suspension 9.9533G polyurethane pads to replace the biscuits. The pads are 2"x2"x1/4" thick with a 7/16" hole (I think the OE pads were about 2" diameter and also about 1/4" thick). The bed bolts have a 12mm shoulder if I recall, so I just drilled out the holes a little to fit the shoulders. They come as an 8-pack, available on Amazon in black (the "G" in part number) or red ("R") and worked great for my needs.
5. Not exactly sure what the "cab to pickup bed" rubber gasket/bumpers are...unless you're talking about the rectangular rubber pads that are between the frame and the bed support beams and each held on by a pair of hex screws. For those, I pulled them off, degreased them, sprayed them black, and re-installed them upside down. Good as new.
Here's a bed-off reference pic from my axle swap project below. Note the harness location on the top of the frame. The pads from item #5 are visible in the pic, too, if those are what you're referring to.
