I agree with everything above; but, have one more thing to add:
The rear suspension on these vehicles has very little extension below ride height. The suspension extension is limited by the shock piston hitting the internal extension stop. These vehicles are extremely stiff in torsion. These things combine to generate a situation where the vehicles 3-wheel way more often than the drivers (self included) realize. The combination of the ELSD and all of the wonderful drive modes in the drive line tend to mask this from the driver. There is no excitement or wheel spin, tire squeal, etc. when a rear wheel is lifted. I've lifted rear wheels when crab walking over soft curbs in 2wd and countless times on 2-tracks while off-road. I would have never known if it weren't for people telling me from outside of the vehicle that they were seeing air under the tires.
The point is, the stock shocks are stroking against the internal extension stop more than most vehicles any of us have ever driven and clearly the OEM shocks can't take it. The 5100's are designed differently. They have several ride height adjustments to lift the rear ride height. I chose to install mine at the lowest, or stock, lift setting. The way the 5100's are designed, this setting gave me nearly an inch of additional extension below ride height when compared to the OEM shocks, which keeps all 4 wheels on the ground much more and keeps the piston from hitting the stop so often.
If you install them yourself, you will notice this because the old spring/shock assembly comes out much easier than when you load the assembly with the new 5100 shock. The overall, fully extended length of the strut assembly is about ~7/8" longer with the 5100's. Hopefully the internal stops are designed more robustly on the 5100's.
I noticed my rear shock OEM leak at about 25K. The truck has 45K now, so 5100's have 20K now and no signs of leaking.
If you change them yourself and want to set suspension torques as specified....pick-up something that will go to 408 ft-lbs. Just saying.
