Putting the tranfser case in neutral is not really the same as disconnecting the drive shaft. When the drive shaft is disconnected neither the drive shaft nor the transfer case output shaft is spinning. If the front hubs are unlocked, the only thingd that are turning as the truck moves are the front wheel bearings, the rear wheel bearing and the rear differential.
With the transer case in neutral. The drive shaft will be rotating, the u-joints flexing, and the rear output shaft on the transer case will be spinning. With the stock transfer case linkage, the only way to get into neutral is to also have it in 4wd, which means (I think) the front output shaft is locked to spin with the rear output shaft. This means that both diffs (front and rear) and the transfer case input & output shafts would be spinning. You could disconnect the linkage and put the transfer case into neutral without going into 4wd, but the rear output shaft would still be spinning.