Following is info I previously received from Roger Oldusedbear.
The Rotten Green Switch is # 15961566.
The Rotten Brown Switch is # 15034355
The above two switches are interchangeable. Buy the cheapest and most readily available one. Both are used for the pump/motor switch position.
The other pressure switch is called simply The Light Switch. It is # 10218778, and is gray in color.
All three of these switches have multiple possibilities regarding source. Chev, GM, Workhorse all tend to be more expensive. NAPA, Carquest etc. may or may not have them in stock or at a good price. Best prices seem to be eBay and Amazon.
We highly recommend carrying a spare pump motor switch and a spare Light Switch. They are often not "locally available."
The NAPA part nbr for the relay is AR282.