Manufacturer Part Number : 223OP74. Application : GMC FM340 Drum Brake Wheel Cylinder Kit. 1958 GMC FM340 Bore: 1.50 In.; Position: Rear Lower;. 1958 GMC FM340 Bore: 1.50 In.; Position: Rear Upper;. 1959 GMC FM340 Bore: 1.50 In.; Position: Rear Lower;.
