Chassis Diagram
 

Does anyone have or know where I can find a chassis diagram/schematics/blueprints of our chassis? (VERY preferable to a shortbed). I'm looking to fabricate some steel that will fit inside the frame rails from a little behind the rear axle to the bumper. It looks like the frame comes out 1 3/8" from the inside to the edge of the rail and 5 3/4" from the inside of the top rail to the inside of the bottom rail. BUT it's not straight and curves up and down in places. Rather than try and trace a cutout it'd be GREAT if there was a diagram of the chassis that shows me the measurements how much it bends up/down and what not. If it had the markings for the holes that'd be great too but I could do them on my own as well.

Have a poke through here, it's probably as close as you're going to come to what you're after:
https://www.fleet.ford.com/truckbbas...7/maintoc.html
You're going to need to look at the F250HD/F350 stuff. The part of the chassis you are looking for the dimensions of is the same long bed or short bed.