Just been unearthing the details... There is one that matches the second photo I posted earlier (141427). Back in 1998 it was owned by Sam Jaffe of Sam Jaffe Autos, NY (MVPA, Army Motors, #83). The other turned out to be the French one, which matches the third photo I posted. The rebuild was covered in Vehicules Militares Magazine, No.8.
There's also another example at Chateau de Blerancourt. http://www.museefrancoamericain.fr/homes/home_id24923_u1l2.htm (click on "premiere guerre mondiale"). Another picture of it here: http://www.ourstory.info/3/Bler/images/pj19.jpg
And there's this one (140196): http://www.pbase.com/goldwing/image/69254801
And this one (141252): http://travelforaircraft.files.wordpress.com/2009/08/blog-model-t-ambulance_mg_8756_dxo_raw.jpg , http://www.google.co.uk/imgres?imgurl=http://www.nationalmuseum.af.mil/shared/media/photodb/photos/051019-F-1234P-013.jpg&imgrefurl=http://www.nationalmuseum.af.mil/factsheets/factsheet.asp%3Fid%3D983&usg=__YUqdzedBhSa9ZILR1b038xo_tag=&h=1197&w=1800&sz=328&hl=en&start=20&sig2=Grkmn8qjh46_L9NzIMELEw&itbs=1&tbnid=r--gb3Une9oAfM:&tbnh=100&tbnw=150&prev=/images%3Fq%3Dambulance%2Bford%2Bt%26hl%3Den%26client%3Dfirefox-a%26sa%3DG%26rls%3Dorg.mozilla:en-GB:official%26gbv%3D2%26tbs%3Disch:1&ei=TmoNTJnMLoj44Aazi_B3 ,