What are P0500 and P0720 codes on 2000 ML 320 Where this sensors located and what are part numbers?

The P0500 code indicates a malfunction in the vehicle speed sensor circuit, while the P0720 code refers to a problem with the output speed sensor. On a 2000 Mercedes-Benz ML320, the vehicle speed sensor is typically located on the transmission, and the output speed sensor is found on the transmission housing as well. For parts, the vehicle speed sensor is often part number A0005402017, and the output speed sensor is typically A0005401617, though it's best to verify with a parts supplier for your specific vehicle.