Originally Posted by Telephonewire
Front weels off the ground (rear wheels on the ground), with the transmission in nutral, I can't rotate both front wheels in the same direction at the same time.
This is normal behavior. If you were able to rotate both front tires in the same direction, it would mean that the center differential was acting as an open differential.
Spinning both front wheels in the same direction would rotate the propshaft between the center differential and front differential. Because the center differential is preventing the front prop shaft from rotating independently, the front wheels can't both be rotated in the same direction.