Pictured above are the three styles of original exhaust manifolds used from 1928 to 1934.
The early style Model A manifold used from 1928 to 1931 has a round outlet cross section and is shown on top. The manifold in the middle was introduced in late 1931 and had a reinforced teardrop shape cross section of the outlet behind the number 4 mounting stud. This design was also used on 1933-34 four cylinder passenger and truck. The manifold on the bottom is for the 1932 Model B.
The first style shown above is the A-9430 used for 1928-31 Model A's. The outlet on this manifold points primarily downward, not rearward.
Original Ford exhaust manifolds have the casting pattern number located on the outboard side as shown above and below.
Pictured above is a late 1931 design A-9430 Model A exhaust manifold with the reinforced teardrop cross section on the outlet behind the number 4 mounting stud.
The 1933-34 Model 40/46 four cylinder cars and commercial exhaust manifold 46-9430 is the same as the Model A manifold shown above, but with the 46-9430 part number cast in the visible surface.
It was Ford's typical practice in that era to renumber parts with the latest production usage prefix, though there was no actual change to the part itself. The Model 46 manifold 46-9430 was just a reincarnation of the last production design Model A exhaust manifold with no change other than part number prefix.
The B-9430 exhaust manifold shown above was used on all 1932 four cylinder cars and trucks and had the outlet port angled much more rearward and less downward compared to a Model A.
Note the rearward angle of the outlet.
The Model B pic above shows the ports and reliefs for the manifold gland rings typical on all 1928-34 exhaust manifolds.