Bill,
Not forgetting the other major change introduced on the A-36A from the NA-73 & NA-83 Mustang I and NA-91 P-51 Mustang/Mustang IA before it of the introduction of the redesigned fixed air intake for the underslung radiator assembly, whereas the earlier versions had the moveable 'alligator mouth' ramp. Also had the different shape and profile propellor blade compared to the earlier 3, slightly wider carburettor air duct above the nose with the associated internal air filter assembly and changes to the radiator assembly design and configuration within the radiator doghouse.