I don't think there is enough information out there to find that figure. Too many branch plants building cars along with the Rouge. The Sport coupes were popular in the beginning but slowly started to lose popularity as the 28/29 production progressed. The first brake system devised for the model A didn't provide a separate E-brake system which was required in the state of Pennsylvania. Ford started revision of the system in February and by late February or early march of 1928, the new system with separate E-brake shoes and drum surfaces was rushed into production. This also required the change of the E-brake lever to the location in front of the shift tower and the characteristic bulges in the rear ends of the running board aprons to get the stuff to fit back there.
Ford wasn't at full production yet but they were on the way. This would make the production figures with the early brake system rather low. The change was likely between engine serial numbers 30,000 and 40,000. Maybe later on cars assembled at branch plants farther away from the Rouge. Previous serial numbers would have the old system.
