One of the first gauges I installed was a vacuum gauge, well...actually two, one for truck vacuum and another for trailer-brake vacuum.
Without a dash-mounted vacuum-gauge, supplemented by a hand-held gauge, diagnosis becomes an expensive guessing game.
As to replacing the actual vacuum-pump, the diaphragm pods are interchangeable universally.
I have a number of them off of Fords, Dodge/Cummins, trailer-brake kits, you name it, and the mounting bolt pattern of the chamber is the same.
On a 1989-1991 Dodge/Cummins, there are TWO vacuum-pump diaphragms, gear-driven off the back side of the timing cover, just ahead of the gear-driven power-steering pump.
The operating rods ride on a CAM on the shaft that drives the power-steering pump.
On the Ford belt-driven units, the CAM is contained within the housing, and is a part of the pulley-shaft.
When the shaft rotates, the CAM works the operating rod in and out, thus pumping the diaphragm.
I hoard up every vacuum-pump I see, sometimes taking two and making one good one, depending on what is ailing them.
I get many good ones that others have condemned and tossed, when they are still good as new.
....Should work for a short time in a pinch if I needed it. How close to the diaphram is the metal case? I also have 2 PSD pumps here but they are serpentine and mine has v-belts.
