I inspected the truck thouroughly. Can't find anything loose. I replaced rear dive shaft u joints and carrier bearing a couple months ago. I still inspected them cuz ya never know. Everything seemed nice and tight. I did spin the axle shafts and the passenger side hits a spot wherever it gets harder to turn.

I guess ill I'll start taking things apart again...

 

Get it up to 65 to reproduce the vibration. Stop and feel the brakes and start with the hot one. I'd guess a caliper or pad problem, even if new.

 

If you've lifted the truck, you may need to shim the carrier bearing. I had to do that when I installed my 2" front leveling kit, and it took all the vibration right out of the truck.

 

There's another handy tool might help you here, it's an IR infrared Laser Temp gun. They're not to expensive, at Harbor freight/Sears like $20. Just point it at the rotors when you come to a stop and you'll see the one that's hanging up. But yes, you can touch the wheel as well, the one that's hanging up will be much hotter. It has many uses in the auto/Mechanics world. Once you get a baseline, checking your ujoints, a misfiring Injector and so on.

 

It is lifted 8" and I have the carrier bearing shimmed accordingly. I borrowed my grandpas temp. Gun and there was no dramatic difference in temp.

Ive been looking on the forums for similar problems. Came across hubs that won't unlock. That is pretty much what the vibration feels like. If that makes sense? But it's only coming from the passenger side.

 

Reach back behind the wheel at the knuckle and try and spin the front axle. If it spins the hub is unlocked but if it doesn't then there's an issue (if you're in 2wd). You can cycle the **** on the auto-locking hub to try and free it. You can also remove it pretty easily. Use a pair of needle nose pliers to remove the snap ring that fits around the auto-locking hub and sits just inside the end of the hub. After that you should be able to wiggle it out. If not it may need to be coaxed out. The first time I removed mine the passenger side was stuck on there. I had to spend some time tapping around it with a rubber mallet before I could work it off. They are non-serviceable (according to Ford) but here's a link to clean it if that's the problem:

Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page

It is worth the time it takes do to this as they are not cheap.

A more remote possibility is the inner (needle) bearing on the hub might be drying up. There's no way to lubricate it. My axle locked up a while back and thought it was my auto-locking hub (took it off and it was fine but the axle still didn't spin). I pulled the hub (took a 2 jaw puller to pull it off) and found all the needles from that inner needle bearing all over jamming the axle.

Obviously it's an extreme case but there's a lot of possibilities for your issue.

 

Yup, as Brian mentioned, grab the axel shaft and see if it's free. If not, it's locked. You should be able to turn the Tcase axle shaft with your hand as well as the axle shafts if they are free'd up or in the unlocked/2wd positon. I've had this happen to me on my truck after being in 4X4 and trying to remove my truck from 4X4. One of the axle's shafts refused to unlock. This is what I did to get it to release.
1. Find a parking lot and drive in figure 8's as tight as you can. You'll hear a bang when it pops out. It'll sound like you broke something.
2. Another time, on a friends truck, I just grabbed the axle shaft with my hands and kept rocking it back and forth until it released.
Hopefully if one is stuck, one of these procedures will help yah to get it to release.

 

Took things apart today. Found out the passenger side is missing one of the round thrust washers. The pattern should be round hexagon round. Is hex round that's it. Would this cause my vibration?