Postwar Mercury (Kiekhaefer) made Wizards not only are not exactly like Mercurys
but same models of Wizards can vary depending upon what components Kiekhaefer had in the parts bin. The other possible reason for differences is that thrifty
persons may have combined two or more damaged outboards to create a usable
motor...I have been known to do that too.
Most likely you have factory examples of using up noncurrent parts inventory.
There are several exhaust/driveshaft housings of different lengths, a short
one I have seen mostly on Mercurys and a longer different design used mostly
on Wizards (both prewar and postwar models singles and twins.) I have no
Post some pictures of your motors for comments.