5th wheel hitch questions

I just got done doing what your considering. I decided to install the hitch and then shop for the fiver. I have a 2016 Duramax, and the Chevy's have the threaded nutserts already installed to accept the brackets. Just look behind the tire at 10 oclock and two oclock. The factory setup is for Curt rails and brackets. They are very stout. If you buy them on Amazon you get the best price. The Curt system is a standard setup that will accept many different hitch's. I did the job myself, and if you do it be aware that there is a left and right bracket, and a front and rear of each one. Don't mistakenly think their the same, as a few guys ended up drilling the wrong holes in their bed. The spacing to receive the hitch on the rails is exactly 22 inches. You do all your measuring from the back edge of the bed to position the rails, then you center them. The rail kit comes with metal spacers that keep you from crushing the bed when you bolt it down, and also the instructions with diagrams. I didn't have to pull the wheels to do the job. As far as choosing a fiver, the manufacturer's started to pay attention to short beds around 2005 to 2006. What you want to pay attention to is the front of the pedestal on the fiver should stick out at least equal to or greater than the front of rig. You need to be real careful of the totally square front ends. Of course the newer ones have the rounded off corners which usually keep you out of trouble. There is a youtube video that shows how to measure a fiver to determine interference with the truck. There is also some video's on installing the brackets and rails. If you do it yourself, your going to need a torque wrench that will go to 120 foot pounds for the brackets etc. Here are the brackets. Good luck with it. Edit; it's been so long since I posted a picture I forgot. Here it is I think.