bronco - front right brake rotor, both calipers, both sets of pads
The right front brake started making some grinding noises. I put off looking at it for about a week since I was having issues with my other vehicles at the time. It turned out one of the brake pads had completely worn down, after less than 20k miles. The metal pad back and the rotor were contacting. The pads on the other side still had about 10k miles left on them. I ended up replacing the left rotor, all the pads, and both calipers (for rebuilt units). Strangely enough the rebuilt calipers are almost cheaper than rebuilding your calipers yourself.