[700rpm]

The oval windows were standard for business coupes after about February 1929 (I haven't been able to confirm when they went into actual production, but around hat time; before that, there were no windows). The correct roof material, according to the judging Standards, was black long-short grain top material. The black car on the right (above message) would be a 1928 business coupe. The car in the middle series looks like the oval window is not correct (too small), but it's hard to tell from a photo.