fasterdammit

So my truck has developed new noise up front, which I'm unable to diagnose. I initially thought it was wheel bearings, but according to a shop - they're fine. At first I noticed a howl once I got up past 30-35mph, but that's now accompanied by some gear noise at low speeds. It's related to wheel speed, because it's still present when I put the truck in neutral (it's a 5spd) and coast. The grinding is very prevalent <5mph as I come to a stop. I can actually feel each little clunk as it slows to a stop. If I were to associate it to anything, I'd say it's like something is jammed into the splines on a rotating shaft: as the shaft rotation slows, each tooth on the spline pushes against the foreign object. And it's not a little tic; I can feel it. The CV boots look ok; nothing obvious stands out - maybe something inside failed and simply hasn't blown the boot apart? I was surprised when the shop said the bearings were fine, and I've half a mind to swap 'em regardless. I wondered if the wheels were out of alignment even, because there are moments (few, far between) when it's not howling or grinding.

More truck detail: 3" OME lift, 35" Nittos

So ... I'm stumped. I've seen a couple other posts around teh intarwebz with the same question ... but no resolution. (Well, one, and my exhaust heat shields are all where they're supposed to be)

Suggestions? Even 'what to take apart first' helps. All greatly appreciated ...

fasterdammit

More info ...

Drove the truck a bit yesterday; swapped it into 4h once the grinding started, and the noise died down quite a bit. It wasn't doing the "each cog on the gear tic" as I came to a stop, either. It wasn't perfectly quiet, but it was better than in 2h. So I'm thinking it's something in the transfer case, or not kicking out of 4x completely when in 2h. Didn't get any time under the truck yet, but we'll see what tomorrow brings.

What all happens when you shift the transfer case between 2H/4H/4L? Is it simply a linkage action, doing all the engaging/disengaging, or does something get switched in the front end somewhere?