I think the last aspect of this thread is the most ignored. I have NO WARRANTY on any of my trucks and I still take my trucks to Cherokee Toyota here in Atlanta. Why? Because I know I will be buying a new Toyota some day, and I want that relationship. I negotiate my labor rates, total costs, etc on things they do to my trucks (mostly coolant, oil, etc work). I know the service manager, parts manager, etc. by simply being there and starting up conversations about "that big land cruiser"....why?
Relationships and understanding. They know what I do. They know I take care of my junk. If I bring something in I can talk about it technically and intelligently. I suspect the only way I would be denied a warranty claim (once I have one) would be if they had a volume issue one month.
For the record...I have replaced a set of front axles, a set of rear axles, a rear diff, a front ring and pinion set, a rear locker, and a lot of other stuff on my 80 with no warranty help from anyone...I wheel it, I break it, I fix it. I know what I am getting into and what can happen. A warranty is meant to help with this on a new vehicle, but honestly it is meant to cover manufacturing flaws (this R&P falls into this category IMHO) and other unforeseen issues with design.
I know they show these lil buggers on rocks all over the place, it makes it a hard call. So what happens when the R&P gets replaced and it breaks again? Since it was a new part number, properly hardened, etc. your going to have a harder time claiming it wasn't abuse...unless you want to lock horns with the design on using that size diff on that size truck, etc.
Slippery slope is all I am saying. I have helped several trucks with this issue now, and always will. I wish everyone with the problem good luck. I can also say that taking those damn things apart so they will roll home sucks
Oh, and remember: It isn't always about trying till you get resolution as much as knowing the right people for the right amount of time so they will go to bat for you.