[Moose]

it is hard to help you without seeing everything but I never had this problem in any car. Looks like you overtightend the diff. Did you sand the diff rings first and compressed the diff spring? And used the right grease everywhere?
Without sanding it and using wrong grease it will always slip.
You can have a look at some youtube clips how to build it. The TLR diff is super good to be honest but the gen2 Diff nut is a nice to have.