Yeah, good luck with getting them to work nicely. They default locked so you are trying to unlock the clutches and if the spacer that holds the large clutch disc isn't the right length, you move the outer clutch back and the inner moves with it due to all the grease they want smeared on everything. Tighten the bolts that hold the hub lock and unlock knob in place just a smidge too tight or unevenly and the knob won't turn.
Yes, they are shit, but it's Yukon, to be expected.
Are you having the issue with the 04 SD unit bearing hubs? I found the perfect spacer is stacking 2 of the spacer rings together (...well, depending which size they send with your kit...). 0.800" total per side.