the Model AR is a mix of parts and was built prior to June 1928, that represented the two famous eras of Fords. It had a multi-disc clutch and different rear end.
The AR is a early model A. You will find some of the parts on the car are carry over Model T parts. Those being items that could be used on the new model. Some subtle difference is that the AR had a red steering wheel rather than the black. The end bolts on the bumpers are unique to the AR only. The brake handle is not on the trans but rather on the drivers side kick panel. The generator is the Model T short pancake type not the traditional long generator.
The early "AR" have alot of different sheet metal design changes,
the grills have holes were the hood lacing loops thru instead of being riveted,
hood side louvers run on a angle from the side seam,
front fenders are shaped different near the apron seam,
running board aprons, have no hump for the brake levers, and get narrow at the rear of the rear fenders on coupe and
roadster have a cut out shape "duckbill" on the back side sedan rear fenders are round on the bottom edge instead of being flat like late fenders
AR also used Model T drum tail light mounted on a round cast bracket mounted to the body, not the fender.
The early headlights did not have the ford logo stamped on them.
Check the book Henry's Lady by Ray Miller. It has come good shots of the carry over parts, and is a good source for the A fan and collector.