Believe me, it is not just a rattle or a squeal. I feel it in the clutch pedal, I feel it in the steering wheel, even in the stick shift! People on the sidewalk turn to check out the noise. If I have not had this previously go away as quickly as it shows up, I would be scared to drive the truck. I, it only seem to be there in January after a long cold (in the teens) spell, then a warm spell (in the mid 30s) and a very humid cold long all day rain. The rest of the year, there is absolutely no problem and the brakes check out as good with significant padding still there and no signs of wear.
The antilock question is curious though. Ever since I purchased the truck (as new) the ABS light has come on and off randomly. The dealership has never been able to figure it out. They have replaced the module with no change. Since then it has been on and off many times without the brake noise so I doubt that it is indicative of anything to do with the noise.
I did forget to mention that I had the emergency brake cables replaced as it was sticking enough to over heat the brakes and prevent me from coasting down small inclines. The noise occurred before the replacement and now after. I doubt that there is a link here either
I will be having a specialist look at it again on Friday. I hope that Thursday's rain/snow event will help enhance it for the next morning. This time, we are going to look for any kind of wear (metal on metal) elsewhere in the system. After all this grinding, something, somewhere, has to show wear...
It feels like a rock gets stuck in the brake pad and grinds on the rotor but there is never any signs of wear on the rotor. Several mechanics have looked at this. Could the caliper be scraping elsewhere than where the pads meet?
Still, other thoughts from here will be helpful.