I am planning to upgrade my single circuit master on my 67 122S to a dual circuit system. I have procured a master/servo combination at a swap meet and wonder if I should be concerned that the master is the Wagner Volvo type (I believe only used in 1968). The unit has the connections to the reservior plugged but no reservoir - so I need one (two) if anyone has any ideas or can suggest another application I can search for a reservior.