open up the center diff and add a HEAVY oil to it. I just got some 120,000 oil in mine, just waiting for me to get around to putting it back togeather. If that doesn't work I'm going to try 300k and/or 500k. There is a center locker, but that adds more strese to all the moving parts. I've read all the numbers I gave you will work, I'm working my way up from the bottem to see what I like best.