I have a 1992 Nissan Pickup extended cab V-6 with 4WD. Over the past couple of months I have noticed a loud whine coming either from the transmissionor the transfer case. It sounds like the front axle is spinning all though the truck is in 2WD and the front hubs are unlocked. Also, I cannot get into 2WD High or Low on the transfer case so I have to drive with the transfer case in neutral. The transfer case will allow me to get into 4WD high or low. I was wondering if this sounds like a transmission or a transfer case problem. And if it is possible to change one without changing the other as it looks like the transfer case is built right into the transmission. Any help would be greatly appreciated.