How do you check if it's the axle joints? I'm getting a weird noise, not a grinding, that starts when I hit 70mph, and goes away after a few minutes. Wheel bearings are fine.

 

to test u-joints, with the truck sitting still, grab hold of the inner half of the u-joint and twist back and forth. there should be no movement at all in the joint. if there is a little bit of movement, it will make a clicking sound. if there is a lot of movement it will make a clacking sound. either one means its shot. you can drive a little more on a click. i would not drive much on a clack...

very easy to test, don't have to jack it up or anything, just slide under the door and its right in front of you.

 

Okay, so the 'axle joints' are the u-joints that attach everything to the end of the axles, right? I'm not that up on axle terminology yet. haha.

 

yup, you are correct


here's a pic of a front axle and ujoint (not my pic)
that's the hub assembly there with wheel studs in it