I recently had the pinion bearings replaced in the rear diff. Since I alleviated that noise, others have arisen. A noticeable "whirring" was occurring in 3rd,4th and 5th gear, consistently around 2500rpm.

Took the van to my mechanic this morning to have him drain/replace the fluids in the tranny and transfer case and look for anything suspicious. There was too much fluid in the transfer case and none in the tranny. Without cracking into either (he is not a transmission specialist and feared a lack of special tools to crack into both the tc and tranny) he's assuming there's a seal that needs to be replaced between the two.

I've been losing myself down the rabbit whole of the search function on this site, coupled with additional google searches.

If anyone has any insight to this issue or a link to an appropriate post/thread I would greatly appreciate knowing what I may be getting myself into.

Ive read a number of threads regarding the 'whirring,' but all of those threads suggest that I shouldn't hear it in 4th. I'm sure most of the noise i was hearing was a lack of fluid in the tranny, but i'ld like to have a better idea before taking it down to a transmission specialist in Twin Falls.

Any help is greatly appreciated.

Thanks, Dave.