The G80's are fine for their intended purpose, like LM7 said earlier, which is slow speed traction, aka off-roading. They only stay "locked" until about 20mph or so, then release.

As long as you don't mash the gas down around corners trying to drift your truck or do excessive donuts, it will hold up. My friend has been spraying 100 shot on his for 40,000 miles with no problems. But for a replacement, Trutrac seems a very popular choice on this site.