The Dash Control Brake Valve is a two button, push-pull control valve housed in a single body which includes a dual circuit supply valve and a check valve
The difference in an MV-2 and MV-3 is pretty simple just check to see how your buttons are mounted to the Valve if the buttons are mounted with a roll pin you have an MV-2 Valve if they screw on you have an MV-3 Valve