The similarity in appearance for the MV-2 Dash Valves (KN20615), and the MV-3 Dash Valves (800523, 065248, 107753) makes it difficult to distinguish between the two items.
However, there is an easy way to identify if your truck has a MV-2 Dash Valve, or a MV-3 Dash Valve.
Simply check how to two buttons are mounted -- If they are mounted using a roll pin, then it is a MV-2 Valve.
If they are mounted by screwing the buttons onto its base, it is a MV-3 Valve.
Please see illustration below:
MV-2 Dash Valve
MV-3 Dash Valve
