Pictured here is a very unusual NOS Ford transmission case 46-7006. At first glance it looks like a typical 1928-31 Model A transmission case, however it carries a 1933-34 Model 46 part number and has a couple of differences to a Model A.
The pic above shows the difference compared to a typical Model A case. This case uses a V8 style retaining pin for the idler shaft and countershaft. It does not use the typical Model A retainer, which is a metal plate bolted to the rear of the case to keep the shafts from coming out or rotating.
According to the 46-7006 drawing release 48 #2 dated 11-22-32 at the Archives, the drawing notes indicate "Use for "A" service, but must be accompanied paired (?) by shafts 46-7111, 46-7140, and pin B-7155-A".
The additional reference part drawings are 46-7111 Countershaft dated 1-12-33, and 46-7140 Reverse Idler Shaft dated 1-12-33.
According to 46-7006 drawing release 48 #24 dated 01-12-33, this part was marked "Obsolete, was 1 Req 46, 46F Chassis".
So in other words, this design was released in late November 1932 for Model A service, but subsequently canceled in early January 1933.
It seems that Ford thought better of disrupting the original design which he had already utilized on 4.5 million cars, and confusing the service requirements of all those cars. I imagine very few 46- prefix transmission parts were ever actually produced for service.
I have looked through all my original Ford 1928 through 1948 vintage US and Canadian parts catalogs, as well as some Australian, British, and New Zealand catalogs, and I have been unable to find any published reference to this case number, or any unique case for a Model A or Model 46 or carrying a 46- prefix.
The regular Model A and B transmission case part numbers were carried for years in service, and there is no indication that this 46-7006 case was ever a marketed service part.
For reference, the normal 1932-34 Model B and Model 46 transmission case is one piece with an integrated bell (clutch) housing.