Do the front wheel hubs spin freely, or do they spin with some resistance and come to a stop somewhat quickly?

If it is spinning freely, all the grease has probably worn out and leaked out of the bearing and it is shot.

 

they do spin somewhat freely, but that is only with me spinning them with my fingers round and round. They sound good and i can hear the bearings and grease when i spin them.

 

Do you hear the hum in the front or rear? Try jacking up the front end, put your hands on the wheel and tire assembly at 12:00 and 6:00, and rock it back and forth. If there is any play the bearing is shot. You may not be able to hear a bearing noise by spinning the wheel while it is in the air since there is no load on it. You can also diagnose a wheel bearing noise while driving...turn the steering wheel left and right and see if the noise changes pitch or gets louder or even goes away. If you turn the wheel left and the noiose gets louder the right bearing is usually at fault, since your loading that side of the truck with it's own weight from body roll. Vice-versa if it happens while turning right. The symptoms sound like a bad wheel bearing, but there definitely are other possibilities...

 

what about the ABS?
isnt there a speed sensor that can go out, and cause the ABS to activate no matter what pressure is used?

 

Yes, the front speed sensors are known to get rust between them and their mating surface moving them further away from the reluctor wheel and getting a false signal. This can usually be felt while driving slowly and braking normal, you'll hear the abs motor activate and the pedal will pulsate. Try driving about 15mph and applying light pedal pressure and see if the ABS activates.

This would not explain the humming noise though...

 

I'm having a similar issue with my '03 RCSB

Any progress made here ?

 

alignment?

 

It distinctly feels like it is coming from the rear end.

I might bolt up with Tahoe or TBSS Wheels / tires to see if it changes anything.