i just broke my Quick loc which is like the lock rite in the rear of my truck. I had less than 500 miles on it and I broke the pin that goes through it in 2 places if I can get a chance I'll post a pic. I dont' have my broken locker to take a pic of it. I think that part of it was due to it not being totally installed correctly but I wasn't pushing it that hard when it did break. I liked it unti it broke and it just didn't seem to hold up the way I wanted it to. I was only running 35's. I'd go with marlins electric locking 3rd if you willing to put out the money. I just orded mine and it is awesome. If your only going to use it in the front go with a hi pinion from them with the locker. the complete 3rd with the locker installed is 895 with 4.10's and 1,299 with 5.29's. I'm assuming you'd have someone do the install and by the time you bought everything for the ARB (gears, compressor ect.) you'd have more into that then you would getting a new 3rd from marlin. I've had arb's before and I liked them but there are rubber pieces that seal the air in them that wear out over time. You have to have air to them for them to stay engaged. The electric units stay locked once they are engaged and if you loose electricity to them you can manually lock them or unlock them by just removing one bolt (takes the motor off) and engage or disengage on the trail. I'd say spend the little bit more in the front for the electric locker if you only going to use 1 selectable locker and get a detroit or something a little stronger in the back.
marlincrawler.com/3rd.html theres the link for ya good luck and tell us what you decide to do