Welcome to the site! The install by Jeff Drew is defiantly first class. I did a fuel cell a year or so ago on my fleetside truck. What I used was an Aluminum 20 Gal. Summit unit (looks to be the same in Jeg's from the pictures) with the GM sending unit. The details are pretty much the same as what Chris did (moved the rear crossmember back all the way & moved the spare tire mount up to be used as a front mount. I made straps from flat stock & notched the rear crossmember to hold them.

I made a skid plate for the bottom that bolts to the tabs that were designed to be the "hold down" tabs, to be legal NHRA/IHRA, the bottom of the cell must be covered.
Some type of notch was needed for the gas filler, but since the ends of the same crossmember need notched for the shackle/hanger, I cut the whole thing out & moved it back 3".
A lid in the floor finishes it up


The stepside is going to add a few slight differences (the wood floor & the fact that the bedsides don't hide the cell from the side).
I did a 2" (in the rear) angled body drop with part of the reason to hide the cell from the side.

As far as mounts. You can get the rubber half from a local store or dealer & the metal half from a dealer or salvage yard. Have fun & post some pictures! Lorne