Originally Posted by brandonjansen
No single mod can void the warranty on your entire truck. Warranty can only be voided if the mod is the cause of the problem with the truck. So explain to me how changing gears to a lower ratio is going to cause a problem?
Well, you'd certainly immediately lose the warranty on the differential and if you had to change the transfer case you'd lose the warranty on that as well. Then, we have to start to talk about how this change would impact the transmission and the control systems for the engine, transmission and transfer case. Realistically speaking, maybe swapping the differential won't make a bit of difference but there's no way to know until you try it. That's an expensive gamble. ANY dealership that wanted to could easily use this as an excuse to not repair pretty much anything in the drivetrain they felt like.
There's no way I'd jeopardize a 100,000 mile powertrain warranty on a $30-$40k truck for this. I bet the OP would be better off to sell his truck and just go buy a new one now that he's learned what he really needs. There's much less risk in this approach and in the long term, I can tell you which one I'd put my trust in.