It's the transfer case unfortunately. Took it to a shop and they put the car on the lift, put it in drive and held the gas in. The transmission sounds quiet but the transfer case is just whirring.

Looks like I'll have to have that rebuilt. Any recommendations on anything I should do to it while it's off?

 

final stupid question. I found someone local selling a NP231 trasnfer case for a Dodge Ram 1500. Since my transfer case is an NP231 as well, is that a direct swap in or would there be any difference between the two?

 

If the transmissions are the same, it might be a direct, easy swap. I had to look and look and look and wait to find a used NP231-D for my 93 Dakota that came out of a truck with the 5.2L V-8 and the four-speed auto tranny. There were others around, but they wouldn't match up because of the spline count on the shaft that mates the tranny to the transfer case.
Did they check your transfer case fluid and change it to see if that would quiet it down? Old worn out or burned lube doesn't do the job well. Might be worth a shot doing that until you can find a transfer case that will drop in your truck. A local and respected tranny shot quoted me $600 to rebuild my old transfer case, but I eventually found a direct swap used transfer case for $150 but I had to make road trip from Tejas to Oklahoma to pick it up.

 

Just a quick suggestion...you could always go to a competitors tranny shop and tell them your situation and that your having someone else handle this problem but you wanted their opinions and ideas if there's any type of special fluid other then stock that you could put in your transfer case to see if it fixes your problem. Or someone on this forum might have a suggestion on a special fluid, you could post a new thread asking that question. You might get lucky and have a $15 fix rather then the cost of a replacement transfer case.

Let us know how it goes!

 

Did you ever have this taken care of? I think I have the same thing going on ... I have a humming sound that starts out at about 35 mph to about 50 mph and then goes away. Not sure where it's coming from but as I'm driving at 45 mph and I turn the wheel a little bit I notice that the sound lightens up. Could it be my tires? not the transfer case? It gets pretty loud right at 40mph ....???? I have a 2002 Durango 4x4 SLT 4.7 L