Thanks for your repply, we were thinking that it was a 1917 or 1918 due to the bumper at the front and different radiator from the K16 you sent in picture.
You're aboslutely right !
Antique patina is very nice but as we are specialized in WW1 history, we have to restore this GMC in the same condition that it was during WW1.
That's why we are searching information before changing anything on this car. Perhaps the plate at the back was in place in WW1, we don't know...
For example, the Dodge at the left of the first picture will stay in that condition, we 'll not change anything on it !
(sorry for my language, I'm french ! )