Buy OEM Audi Part # 4E0407509G (4E0-407-509-G, 4E0407509K). Suspension Control Arm (Rear, Upper). A6, from VIN 4F8018001. A6; Rear; Left. Suspension Control Arm - Repair or Replace Control arms

Cntl arm. Link. Suspension Control Arm.
Exc.Sport Suspension. From Chassis/VIN 4F-8-018 001. From Chassis/VIN 4F-8-122 885. Incl.Ball Joint & Bushings. Suspension component that connects and provides pivotal movement of the Steering Knuckle to the vehicle.

Suspension Control Arm

Fits A6

A6, from VIN 4F8018001. A6; Rear; Left.
Suspension Control Arm - Repair or Replace
Control arms often don’t fail on their own, although their associated bushings can break or wear causing a clunk noise when your Audi goes over bumps or changes speed rapidly—whether braking or under hard acceleration. Control arms can also sometimes become bent, causing your vehicle to pull to the left or right.