4 years ago an article mentioned that there are no WW1 1917 ambulances, it seems they didn't look around enough, this one has been in a small museum in San Antonio

http://www.odcloth.com/1955m170.html

the article was in Hagerty Magazine about a guy that built a 1917 Ford Ambulance  http://justacarguy.blogspot.com/2011/12/1917-ford-ww1-military-ambulance-none.html

but there is also one in Kingston Texas

found on https://www.facebook.com/pages/T-Fords-of-Texas/202854526473290