Neithe
Were you there? Unless you were there and have proof of that happening, you have no clue what you’re talking about.
Neither the transfer case nor the front diff causes the symptoms described.. however, the symptoms described is exactly spot on consistent with what a failed crush sleeve (reduces or eliminates pinon preload) and/or a backed off pinon nut/ improperly torqued Pinon nut.
What happens is when using go to accelerate you'll get a slip followed by a tailbump caused by the rear driveshaft starting to spin prior to engaging the ring gear due to aforementioned worn/damaged Pinon seal/crushsleeve and the play it creates. As it rotates and inertia drives it rearward back to where it normally belongs in proper permanent engagement..
Makes perfect sense to me.. I've replaced several dozen Pinon assemblies on gmt400 and gmt800 as well as have rebuilt many transfer cases as well. And have had my fair share of hundreds of hours with front diffs on the bench and in hand.. so no sir, needing to be there to watch someone who may have known better st the time or was in a vulnerable situation and in need of immediate repair without regard to sensible reasoning of the symptoms vs the proposed repair, fork over money unfairly suckered from him is not necessary for diagnosis. No disrespect intended.. Was more upset knowing thrbdealer took you for a couple grand than anything else, I didn't mean to come off with a bad demeanor and my appologies for doing so as I realize I was a little bothered when I wrote that, my mistake