Rumbling noise at speed in 4H

I noticed a rumbling noise coming from the front of the vehicle at 60+ mph when letting go off the gas. It only happens when the 4H is engaged.
It's fairly similar to the sound of a bad wheel bearing.

Any ideas?

 

Transfer case engaged - is the vehicle new to you or is it louder than it used to be? Has the fluid ever been changed?

 

Yes, got the truck a few months ago. I haven't had to keep the 4H engaged at highway speed until now so never noticed.
I've never had that sound with my 4Runner. Is this a Tundra thing?
My guess is the transfer case fluid has never been changed, I will probably get that done.

 

Is it because your going 60mph while in 4H??

 

There is no reason you shouldn't be able to drive 60mph in 4H, just have to shift to 4H when below 60.

 

You’re right, manual says you only need to be below 62mph when you shift into 4H.

I’d follow up with is there a reason why you should drive 60+mph in 4H? I can’t picture a need to drive that fast if conditions warrant 4x4.

 

Right now we have freezing rain that creates a lot of black ice patches. I don't have a full understanding of how 4x4 works (I usually only use it to get unstuck when in deep snow, etc) but the truck felt quite a bit more stable once engaged.

 

Sorry I think I kinda misread your question. I have the 4x4 engaged because of ice (driving slow in those conditions). I only go 60+mph when it seems safe to do so (which isn't often).

 

Looking at the fluid wouldn’t hurt but I’m guessing it’s normal. I would describe it as a “whooshing” sound but the driveline definitely can be heard when getting up to speed in 4H or 4L.

 

Ok that's reassuring. Thanks!