Hi, I am not sure about the duplex pump at the mill in Toulumne. Over the years alot of the westside equipment has been lost or scattered all over. I do know that the big coreless steam mill engine is still at the mill area in Toulumne.
As for the duplex pump that WAS on the #7, it was for fire fighting. This pump never really funtioned properly or reliably at Roaring Camp,so it was not rebuilt or reinstalled. There is however a fire hose conection off the firemans side branch pipe that work good as well as the deck hose located on the firemans side.
The current owners of the Weststde mill site is the Miwok tribe of Toulumne. They might know more about the duplex pump that you are intersted in.
Phil