Drive 16 Teeth - Counter Clockwise Rotation. Mounting hole Centres - 58MM Drive Pinion Dia. 40MM For single cylinder aluminium block engine 4-1/4" (108mm) housing (length of black part) Replacement Briggs and Stratton Starter Motor + BONUS DRIVE GEAR HOW TO CHECK IF THIS STARTER MOTOR IS THE ONE YOU NEED: Count the number of drive teeth on your starter motor’s drive gear.There should be 16 teeth. Check what the drive gear on your old starter motor is made from. If it is plastic or aluminium then this starter is suitable. Measure the housing of your starter motor. If it is between 90-110mm then this starter is suitable If your old Briggs starter motor has a plastic or aluminium drive gear, 16 teeth and a housing measurement between 90-110mm then this starter is a suitable replacement. SPECIFICATIONS: 12 Volt Drive 16 Teeth - Counter Clockwise Rotation. Mounting hole Centres - 58MM Drive Pinion Dia. 40MM For single cylinder aluminium block engine. 4-1/4" (108mm) housing (length of black part)