Hey everyone, I recently picked up a 1966 Ford Custom 500 and am in the process of restoring it. I'm somewhat new to car repair so I'm learning as I go so bear with me. Every time I come to a stop I can hear a loud clunk sound come from the rear of the car, driver side I believe. Initially I thought it was the drum brakes in the back but after taking things apart the brakes actually look like they're in really good shape. I'm still going to do a rebuild, new hardware, resurface drums, and replace wheel cylinder but was wondering if that doesn't turn out to be the problem what else could cause this? It only happens when applying the brakes to slow down at like a stop sign. It does not clunk when applying the brakes to slow down at higher speeds. I should also note that as I was taking apart the brake on the driver side I noticed a ton of gunk and grease built up behind the backing plate. It was all caked in the ridges of the rear of the backing plate. When I looked behind the passenger side of the backing plate it looked totally clean. I'm assuming this could also be the cause? What would this be? Thank you for any tips.