Briggs & Stratton 83132-1040-F1 Horizontal XR550 Professional Series Engine, 127cc, 5.50 Gross Torque, 5/8″ x 2-27/64″ Crankshaft, 1/4″-28 Drilled & Tapped, 3/16″ Keyway, 2.1 qt Fuel Tank, Replaces 83132-0040-B1