For what its worth I had a Detroit EZ locker in my WJ and it was complete TRASH! It passed the spin test with flying colors, and would unlock like it was designed to going around turns, but wouldn't remain locked when on the gas going in a straight line. The locker would disengage and pop, sending the back end sharply to the pass. side. Kept it in the jeep for all of about 48 hours, constantly telling myself once it broke in, it'd get better. 
no dice. Now I've got a Lock-rite in the front axle and no problems.
Also had a friend just swap an 8.8 into his ZJ. He installed an EZ locker and had the same problem.
