Rear Subframe Mounting Bushes This bush fits saloon and hatch models only NOT ESTATE VERSIONS. OE Numbers 1S71-5K817-AC – 1S71-5K818-AC – 1404976 – 1404977. – The rear subframe is held to the body with 4 rubber bushes, these bushes fail making the rear subframe to come away from the body, this causes knocking from the rear and is an MOT failure. PFR19-910 are an easy to fit reliable fix to this problem.