OK, first a little back ground. Abs light was coming on and off and speedometer was jumping. Took to ford dealer and the speed sensor was full of metal shavings. Had rear end totally rebuilt including axle bearings. Now I have a chirping noise coming from underneath the truck only after it has warmed up a bit. Walked/jogged next to truck while listening and sound seems to be in time with wheel rotation(or u joints?) The noise is def a chirp and not a squeak. Any thoughts?

 

Sounds like U-joints. Second guess would be something stuck in/near the rotor.

 

What's easiest way to ck u joints? Just crawl under and see if there is any play? Or do rear wheels need to be off ground?

 

Jack up one rear wheel, chock the front one, and have someone rotate the wheel back and forth while you are taking a close look at the u-joints with a light. Look for reddish dust and movement at the cross-piece. Grab the drive-shaft with your gloved hands to give it some resistance while turning if needed.

 

Thanks...will do and let you know.

 

I posted above about my failure far far from home. It turned out that my own little chirp/ squeak turned out to be a completely failed front hub bearing. It sounded so completely harmless, like the end of life squeak you get from worn brake pads. Check your wheel bearings!

 

No, greaSE YOUR FRONT BEARINGS

 

4wd front hubs/bearings are sealed. They are non servisable!

 

not true..........

 

Sure they are, IF you have the ABS sensor hole. I bought one of these little gizmos from Snowseeker (Andy) and pumped about 20-22 pumps of Mobil 1 red synth grease into each hub bearing, 30k miles later and they are still happy (98k total miles on them). https://www.ford-trucks.com/forums/1...-hub-zerk.html
Brent also has a how to on greasing them that involves a funnel and some small bore tubing that works.

 

I have never read that thread...

 

Do a search.

 

You can't inspect, clean or truly inspect the bearings. You can only fill up a cavity with grease! I admit this is better than nothing but not really servicing either!

 

True, But it is about the best that we can do.

 

Yes, it is great servicing. If your bearings are still good they are probably very low on grease and the new grease fills the cavity. That's like saying anything with a zerk fitting is not really serviceable. I shot at least a small tube of much needed grease into mine 3 years ago and they are working fine.
If you are not a believer just wait and buy new ones.