I am curious what type of covering would have originally been on the floor of my 1941 fire truck; I’m assuming some kind of rubber floor covering?
I have no idea if it is a custom open cab model. A 1941 standard closed cab truck had a rubber floor mat. Reproductions are available but I have not had good luck with their quality and would strongly urge you to avoid them. A very inexpensive alternate is to use 1/4 inch thick horse stall matting rubber material purchased by the foot available at farm stores. In the US, Tractor Supply is a good source.