I did my once in a blue moon total tear down re and re this past week, I had it stripped to the last nut and bolt all spread out in front of me. So I'm putting it back together working on the center diff/brake assembly and I could not get it to mesh properly! An hour later after pulling the remaining hairs I have out I realized I installed one of the F/R diff pinions in instead the center diff pinion, they look almost Identical but there not! Duhh!