That could explain the clunking at low speeds, not sure if it is the clunk I hear during gear changes. When I put the car in reverse it clunks so I think that is the Locker since the car is barely moving. I don't think the Calvert setup would make any noise when the car is barely moving, especially in reverse. When driving at low speeds over rough pavement I hear a fair amount of clunking from the rear end and I'm guessing that noise is the Calvert load bar hitting the springs. From inside the car it all kind of sounds the same but I think the noises are caused by different things.