Yes, you can swap the front seats for a bench but just keep in mind that unless you find a split bench the *entire* thing will have to be bent forward everytime someone gets into or out of the backseat regardless of which side the use. It'll still work but it's a pain in the ass. The Broncos share a common floorpan with all of the F-trucks so anything from any other Bronco or F-truck will work. Ck with Billy *******, he's been looking into this for sometime now.
As far as tailgates go, join the club. You're fortunate in that *any* 80-92 tailgate will fit your truck. The exterior trim changes every few years but all of the tailgates from the 3rd generation Broncos are interchangeable. Salvage yards are the most common place to look but I'd keep a close eye on CraigsList as well because a LOT of guys score good parts there. Depsnding on just HOW badly you want the parts you might consider keeping your eyes open for a parts truck with a solid tailgate. Buy it, swap tailgates & then either resell it as a package deal or part it out yourself to recoup the expenses (big hint, if you part it out yourself you'll probably MAKE money on the deal and when you've picked the carcass clean you can still get a local salvage yard to haul it away for free)
