Simplex Automatic scooters were made from about 1957-1960. 125 cc standard engine, 150 cc optional. Lots of info on www.simplexservi-cycle.com. You are missing the side covers (flat sheet metal) Serial number is on the frame under the seat. Engine serial number is on the engine case below the output shaft. Torque converter drive, about 4 hp, 2 stroke. Made in New Orleans.