Early casting with double windows and Die-cast wheels - hard to date this one.

Nice No 6 with a 1918 date on the side, but the casting almost looks older?

The one above has a 1921 date on it but is similar to earlier ones,  the one below a 1922 date. They would appear identical except for the square key mount on the later one.

The example above has a 1924 date on the motor.