front bench and rear bench seats

[7.3HeavyHauler]

heres the story, I traded my 01 Ram 2500 for this 99 F250, the guy I got it from said it came from the factory without the rear bench seat..I blew him off as I had other plans and didn't really care about the back bench seat, so anyways I busted out my rear window on accident, the post in the general discussion, but after vacuuming out all the glass I noticed that there are no holes whatsoever for the rear bench to mount to and also no seatbelts, nodda, nothing, ziltch. Scratching my head over that one, and heres the other thing, on the front bench seat to front mounting torx screws, I have 5, 1/8" thick fender washers?!?!?!?! would Ford really do that? I am guessing my truck has a history that I'll never figure out, does anybody else have fender washers as spacers on their front mounting bolts?