I put a spartan locker in the rear of my ROXOR this past weekend and have tested it significantly all week. IT'S GREAT. less than 5 hrs to install and I'm no pro. The directions sucked but the end result was worth it. I don't know if it's the spartan locker, the good fit or the narrow stance of the ROXOR or possibly a combo of all the above but it is super smooth and quiet. No typical lunch box locker noise (ratcheting, pops or clicks). I went up a mud 45 degree twisty hill on my ranch with nairy a slip, with factory open diffs I was slipping and sliding and had to back down half way up! Seriously get in touch with Wyatt from on the rox fabrication and he will get you started. Steve their gear guy was awsome and talked me through all the things I was unfamiliar with (which was alot). Just be for-warned, you will need a complete socket set, metric and standard, a slide hammer to pull the axels, a wheel puller to pull the hubs (8 ton 7 inch wheel puller worked fine as long as I had a leverage bar, those f******S are on tight!) And a torqe wrench. On the rox was also helpful in some ROXOR specific directions for the install for instance the bolts on the ring gear are reverse thread. Overall I'm over the moon happy with the results and i would think twice before shelling ouT over 2 grand to your local dealer after install and tax to put in their ox locker (def a great product, just spendy) I'll save my money for the stage 2 tune through disel freaks lol.