Lots of good input here already and I know how hard of a decision it was for me picking my new axle gears. I chose 4.88 and just before the shop ordered the 4.88 he called and asked if I'd rather have 5.13 from AAM. Hell yeah brother.
I went 5.13 and ran 35s for 25k miles and loved it. Even on the interstate, and I live where 20 over the limit won't even get stink eye from a trooper. **** you not.
But the plan was 37s. So I followed all these guys trying to figure out my next tire. Load, diameter, width, weight, cost and availability all working my brain. But finally now it is.
I've got maybe 1000 miles on the setup, all pavement. For me I couldnt have gone any higher and been satisfied. Actually, 5.29 would be great with my 37s. BUT I live at 7000ft and I have a 6 speed.
Sea level, 37s, 5.13s and an 8 speed being maybe perfect for me. 4.88 would probably be almost as nice an experience but 5.13 is AAM, so that's where I go.
The 5.13 availability from AAM is because that ratio is offered as an option for RAM 3500. As you know not for ours. I think you've got a chance to have it installed under warranty, at least enough of a hope I would call two or three dealerships and ask. But the odds probably lean away from warranty since the option wasn't there in the beginning for 2500, but I really hope they do. I would love to read that kind of service and manu faith is coming from RAM.
Good axle shop probably $1000 cheaper then dealership (guessing) and your diffs are going to be bomb proof. I know you had some previous trouble but mine lead me to believe in yours.
Good luck, nice truck too!
'16 PWagon with a badass Greene tune feed'n & Fire'n 6.4L 6spd // 5.13 AAM // 37" KM3, -24mm // DOR, Purple Cranium // CAI, ARH, Solo Mach44 // z36, EBC // Custom Graphics, AVS, 4% VLT // Morimoto, Rigid, Diode Dynamics // Alfa, Diablo //.................