MTH Proto-Sound 3.0 Upgrade Kits for Steam, Diesel and Electric 3 Rail Engines. Convert most 3 Rail O Gauge Locomotives with DC Can Motors and a flywheel to MTH DCS Command System. We are an MTH Authorized Service Center and Upgrade Center. Give our shop a call or send an email for an estimate to upgrade your locomotive. We will also repair your MTH locomotive even if it was not purchased from us. Call or email for details.