Transmission slips when shifting from 2 to 3 going down hill.

[Chip]

That's what I'm doing is using engine breaking and I'm shifting up when the grade reduces. I've had two speed transfer cases in other trucks including a Jeep Rubicon that never seem to let go like that. It just seems it can't find the gear, free falls and when the gear finally engages it slams everything forward, enough force to set my dog flying into the dashboard. Bear in mind it was a really steep hill.