I got screwed into an "oem replacement" sending unit... I also have a 97 and when they pulled the part up on the computer at the parts store it gave me one from a nbs... I started at 4pm at work and needed to be out at 6pm... I got the bed off (2 dudes no lift) and found out the part was wrong so I used a shop truck and went to return it and they didnt have a delco one so I had to get a **** one cause I needed the truck.... One of the only products I registered the warranty... cause when it dies 11 months after putting it in they're buying me a delco one and paying me to put it in.
now that my stories over heres my advice... Pulling the bed is the way to go! but the next time I do it Im cutting a hole... GET A DELCO pump/sending unit. to pull the bed
1) undo taillight plugs (no cutting required)
2) open gas cap, undo the 3 hex head bolts not the torx, pull the gas cap off, push the neck through, reach underneath and put the cap back on.
3) crawl underneath and undo the one 10mm attaching the filler neck ground strap to the bed cross member
4) undo the 8 bed bolts 18mm socket (yes 8 bolts to hold a shortbed on... little overkill)
5) pull the bed off, you have to lift it OVER the bumper so wear your weight belt