I have a HP D44 and a D60 from a 78 F250 under my 95 YJ. I put a Spartan locker in the 44 about a year ago. It worked great on the trail. I never noticed clicking noises coming from it, but then again I don't drive on the road much and I have lock-outs. I pulled the spartan out about 2 months ago though because it was eating up u-joints. I exploded 4 of them in a year, along with taking out 2 sets of CrMo axle shafts! My assumption for what caused this is when the locker does unlock and you are still under throttle, it immediately re-engages. This is quite a bit of shock load on components (and I'm still running the stock engine, tranny and t-case... 35" tires). After breaking stock u-joints, I upgraded to Alloy USA X-joints and these exploded as well. I've since gone to a True-trac up front. I've only had it out a couple times, but for the most part it is staying engaged. I have seen it unlock a couple times, but in my mind, this is just saving parts damage.