I have an '03 an at 38k miles I started getting a noise from the LF wheel area.
It sounded similar to a hub-bearing but almost like a rattle between the backing plate and rotor only at 40mph. Weird huh? No noise in the hub bearing, no rock in the backing plate.

Conclusion:
Spindle hub nut castle cap. The cap that goes over the spindle nut and has a cotter pin through it had worked a little loose and was rattleing only at 40mph. It has a rubber coating where it contacts the nut, but it had a rattle on the spindle itself. Oblonged the cap with a hammer---noise gone.

I hope this easy fix helps someone else keep from buying a new hub bearing.

 

hey....wondering if you could tell me if that noise stopped when you stepped on the brakes....because i have a similar noise but stops when i step on the brakes.....hope this is the same problem

 

No, braking, accelerating or turning made no difference. Just speed....40MPH.

If you have a noise that goes away when braking, it is brake related. Bevel the pads, lube the sliders as well as all contact points between the pad backing and the caliper and caliper bridge. These are the contact points that set up harmonics tha cause noise. Lubricate these and the noise will go away.

 

cool man...thanks alot good luck with your truck