2020 2500 Sierra Crew Cab with Factory prep
Five holes in total
From the front of the bed the first pair is 37" aft of the front of the bed, the gooseneck hole is 8"behind the first pair. The second pair is 13" behind the first pair. There is 21" between each pair and from the inside of the bed at the wheel well the first hole is hole is 16" inboard. Obviously the same on the other side.
If your going to pull a 5er in the next month you need to convert to one of the gooseneck hitches.
I just installed an Anderson Ultimate CONNECTION along with an Andersen 3249 connection kit. Everything fits and works as advertised. I tried a Curt 60692 for the chains and ran into a massive problem with clearance of the Curt loops from the Andersen hitch. Seethe Curt kit back. The gooseneck location is further aft than my 2013 by at least 3 inches. The 2020 will get bags as soon as they are available as it squats 2.5 inches with the 5er hooked up. ANY 2019 GMC GOOSENECK BALL FITS IN A 2020 DESPITE LOTS OF MISINFORMATION FROM MULTIPLE SOURCES OUT THERE. I do not know if I am completely sold on the Anderson so far. I have not trailered with it yet and leave tomorrow morning for 10 days. Hooking up the Andersen in the drive is a bit more of a pain than my old B&W to get the gooseneck ball fore and aft the correct amount. The in bed camera is not much help but I need to take some time to see if I can make a few alignment marks to make it easy. The second concern I have is having to raise the front of the 5er about 5 inches to get off the hitch. 2.5 inches on the squat and 2.5 inches of the ball. Half of that will go away when I get the bags on it. I will post a big report once I get trailering. I put in the break in miles and so far like the truck. the 10 spd takes a bit getting use to but there are tons of really nice features that my old truck did not have.