[amati5]

Are you on slippery surfaces when you get these noises? If you are, they are probably the anti-locks working and this isn't a problem, that is how they sound.

Yup, I had this loud noise (one time only) when I was going down the slope on my drive way. It was LOUD, I thought something came loose. Happened one time and that was it. Maybe that was when I wasn't used to the new truck's brakes. Usually the when the abs is active (from my other cars), it makes a grindding sound, but this one made one loud thunk.