Yup, but you have to do both axles and they need to be set up by a specialist to adjust the proper preload and backlash. I did two axles with the service manuals handy. I don't ever want to do another one.
I'm still confused on what you were told about stress. The stress comes from the rubber control arm bushings being in a permanent twist from the suspension being lowered to raise the truck. The gear ratio has noting to do with that. 4.56s will give you quicker acceleration and usually lower fuel mileage but it won't change anything else. I can see where someone might think there would be less pressure on the universal joints but they can take that. The wear is also a factor of how far the needle bearings roll back and forth in the cups each drive shaft revolution. At the design height the cups are meant to turn back and forth a little so the needle bearings never stay in one spot and create dents in the rolling surfaces. Raising the truck increases the drive shaft angle which does not eliminate that rolling back and forth but it makes them roll further which I suppose could make them wear faster.
I think I'd talk with a few more people before you go to such an extreme measure of changing gear ratio without knowing what they're trying to solve. The impression I get is someone is trying to sell you an unneeded service.
Wednesday, August 15th, 2012 AT 4:40 AM