103546 - 2005-2010 Ford Mustang Rear Control Arm KitP N 1058, Optional Spacer Kit: The optional spacer kit is designed to reduce a factory Ford 16mm hole to 14mm to prevent rear suspension movement which leads to noise. The factory Ford chassis mount features a 16mm hole while using a 14mm bolt. This hole slop leads to noise during acceleration and braking. The stepped spacers reduce the hole size from 16mm to 14mm. Note: Spacer kit is designed to work with the factory upper control arm mount. Most