What is this noise and whats producing it? It only happens when i apply the brakes at a normal to slow pace. If i have to suddenly push the brakes i dont really hear the tick/click. Since I hear it only when i drive and brake, i can't really tell from the outside but from the driver seat it sounds like its def coming from the left side and somewhere near the upper back portion of the tire/brake.

1999 F150 V6 4.2 4x4