If you have an electric clutch you will have to purchase an engine with a 9 amp or larger alternator or reuse the stator and regulator off of your old engine. Briggs Intek Single cylinder engine 31P777  & 31P977-1066-E1. If your engine has a fuel pump, you will need to purchase and engine with a fuel pump or reuse you dipstick tube, fuel pump, all vacuum and fuel lines, and fuel pump bracket. Briggs Intek Twin 445777 407777-0121 with a 1" shaft. Some also had a Kohler CV730-0018 which has a 1" x 3 5/32" shaft. You cannot interchange the Briggs and the Kohler engines, they are totally different. You can use a Command Twin listed below, there may be minor differences however parts would be interchangeable if needed.