Spartan Lockers are in my experience are the worst. I bought 2 of these during my one ton build. Having had Aussie Lockers and Lock-Right lockers in the past with great success, and being budget build it seemed like a good idea.
The first one wore out after a year of wheeling. It was installed in my front axle and oddest thing is that with the lock out hubs the carrier never spun much. I ended up removing it last winter in favor for a grizzly. Upon inspection it had a lot of chipped teeth on the side gears and cams.
Now 2 years after the original install, I broke the ring gear, I pulled the Spartan locker out of the rear to find this: