Nice issue, one again. Liked Mark Miller's "Sky of Blue & Sea of Green".
The photo of his grandfather Roy in a 1920s racer is obviously in a version of a Ford Model T. Not many other fords around at the time. Many racers created their own custom versions in order to gain an advantage. What specific variation of a Model T it is, I don't know. Unique features are: No right exhaust, the very short tail and steel spoke wheels. Maybe some expert in Model T vintage racers can shed more light on it.