They are open. No limited slip ever offered for the KK. The "brake lock diff" is nothing mote than the ABS sensing one wheel turning faster than the other on the same axle and applying the brake allowing the power to go to the other wheel. Fancy traction control. Now, picture a Detroit trutrac in the diff. On the rare occasion when one wheel may turn without, the brake will automatically be applied allowing the other wheel to turn. It seems like the perfect compliment for our KK's. My traction control hasn't kicked in yet but I haven't been able to really check it out yet. I have heard great things about the performance of that set up.
2010 KK Sport, Detoures Knucklebone & backbone, smittybilt XRC 10, rigid led lights, R/L sliders & rack, cb, EMT2, R/K 15x7, OME, JBA, mopar skids & hitch, headlight covers, 4.10's and TruTracs