2000 Tahoe Z71

Well, I started hearing this high pitched chirping/squeaking sound coming from the front right/front end, so I figure brake indicators, checked them, not touching.

So now I figure it's the hub assembly since I was at 80k and the ABS was going bad, so I order new hubs, installed them both, new brake pads took it for a test drive and son of a B#### it still chirped.

So I played with the 2w to 4w drive button, on the test drive (which I should have done first) and found that as soon as it went into 4w High the sound or chirp stops, then when I placed it back into 2w high it took about a minute or so for the sound/chirp to come back.

What could this be? Anyone have a problem like this?

Thanks