To determine if such a silencer is currently available, I would recommend checking with authorized Royal Enfield dealerships or contacting motorcycle accessory stores that specialize in Royal Enfield parts. They will have the most up-to-date information on product availability and can assist you in finding a BS3-type silencer for your Royal Enfield Classic 350. Additionally, online platforms, such as e-commerce websites or Royal Enfield enthusiast forums, may provide options for purchasing aftermarket silencers. Remember to verify the compatibility of any product you consider purchasing to ensure it matches the specifications of your motorcycle.