I am guessing that there were metal plates on the floorboards near the pedals for 1918 correct? What kind of screws were used to hold them on?
Early cars had round head screws, later on the pedal plates were just folded around the wood to be held in place. Wind deflectors on late cars were held by hollow rivets. See this thread:
Thank you guys.
John Regan makes faithful reproductions of the flat pedal and brake lever trim, at least through 1917.
It may be possible that it was carried over into the 1918 model year. You can read the record of changes if you open the "certificate of authenticity" on the webpage.
Both my roadster (May 1917) and my father's touring (July 1917 and last month of model year) have the flat metal trim which is held down with screws. They do not have the "lugs" to which John Regan refers in his "certificate of authenticity."
Since I'm not up to going out to the garage this morning, I'm guessing a #8X 1/2" R.H. slotted.