Haha dude... everspeed is 100% correct and it is 100% operator error. If it is the center diff gears you would hear a bunch of grinding and if the center diff gears don't mesh correctly than YOU didn't read the instructions right by not using shims. I didn't build a tq but every other center diff I have taken apart has shims pretty much behind every gear in there. If YOU didn't tighten down the flywheel enough on the motor than the crankshaft is going to spin instead of the flywheel spinning with it. If the flywheel doesn't spin than neither do the clutchs because the clutchs are mounted to the flywheel.

P.S. Did you put any oil in the center diff.... or the front and rear for that matter?