Mark found this jewel of a PDF at Roscommonequipment.com. We’ve seen a few of these fire jeeps for sale over the years. This document provides some insights into how the pumps work and the type of modifications that were added. The document contains instructions, specifications and detailed drawings.
You can see the whole PDF here: http://www.roscommonequipmentcenter.com/Project%204_Jeep%20Tanker%20Handbook.pdf
Here’s an example of one jeep that was for sale last year. I thought there was another one, but I can’t find it at the moment.