[Joe K]

My first recollection was that the early 28-29 radiators were the same between the cars and the truck. This would have been the era of the "funnel top" radiator which had tubes of superior heat release compared to later production. (oval tubes instead of round or losenge shape?)

But I think it has been noted in the literature that the AA trucks of both early and late production suffered a bit with a "gap" that is present or can develop between the radiator shell and the hood - caused by the larger (thicker as in more rows) AA radiator? Hence, finally later in production, the development of the thicker "truck" radiator shell (the one without the "widow's peak") to formally close this gap.

This end thought is proven out in my 1931 parts list (available list reprint - others have been done since then) where the A-8005-AR radiator (car) lists for $15.50 and the AA-8005-AR radiator lists for $17. A larger (thicker) radiator is obviously more money? The truck radiator shell shows for the taller 30-31 radiator but no equivalent part shows for the 28-29 radiator? Maybe the gap was "adjustable" or not considered significant enough for 28-29 to warrant a fix?

Still the commentary about "gapping" must be from this transition to and availability of two radiators? The A and AA radiators MIGHT have been the same for earliest production?

I guess we need to look at the early parts list.

Joe K