Uh Oh! These are Genuine Gears. They were cheap and with a lifetime warranty I figured I couldn't go wrong. I've run these in my K5 for about 4 years with no problems. My buddy who works at 4 wheel parts said in order to reduce costs these gears are not pre-run at the factory so the tend to wear in a little more than other gears. I set the backlash on the tight side to help compensate for the wear and they could also be adjusted again later I guess. But it's not a big deal for me since I will put very little miles on them with mostly trail driving.
What else do you know about these gears other than the above?
Genuine Gear sucks. Yes, they have a lifetime warranty, but your going to be replacing them often. For their price, Yukon or etc is way better, even though they only have a ~1 year warranty. Bottom line all gears are junk when not setup correctly. Genuine's are just worse. They are hard to get setup correctly - even using their specs!
Too much backlash will surely kill them. Set them up with .007-8 BL and favor the TOE on the pattern...