Today I was driving about 35 mph when I drove over a small patch of rough pavement and I started feeling and hearing a rumbling sound from the right side of my truck.

It felt like I was driving on a dirt road so thinking it may be my flex plate I put the truck in neutral and the rpms went to idle and the rumbling stayed consisten with the tire rotation. When I get to about 5mph it just clears up and drives fine until I hit another bump.

Is this my wheel bearing?

 

Maybe. If you put your front hubs in the lock position, (leave transfer case in 2 hi), and drive it around and it doesn't happen again, chances are it's the stub axle needle bearings.

 

What would the fix for that be?

 

If it is, in fact, the needle bearings, you'll need to replace them. You'll need to look at the mating surface on the stub axle. If it is badly worn or damaged as well, you'll need to replace the stub axle.

 

The wheel hub is sold as an assembly and Ford considers the bearing "non-serviceable", which means the dealer will want you to replace the whole hub. Some guys on here have successfully rebuilt with new needle bearings, but if you have a lot of miles on the existing hub you may want to change the whole assembly to get a fresh wheel bearing also.

 

Locked the hub and the noise stopped, gonna drive like that until I have time to mess with it.
Thanks guys!

 

Lock the hub on the opposite side too.

 

I would look into greasing the needle bearing in the hub. Here's a link.
Welcome to guzzle's 4x4 Needle Bearing Maintenance Web Page

Might as well grease the non serviceable bearing also.
https://www.ford-trucks.com/forums/1...-bearings.html

 

Experience has taught me over the years that by the time you can "feel" a bad bearing, it is too late for grease. It will only buy you a little time at best.