Lynn,
If you look at the housing on this web site and the housing photo you
provided, it would appear that the housing in your photo is ground down
about .5 on the side we are looking at, the pump housing side( not the rotor
wear side).

I figured that a grind job would automatically cut down the all the surface
to the same height, and might affect the pump housing depth - but I suppose
it's possible to do the perimeter without touching the pump itself.

Either that, or it's a different housing - later perhaps?
George (down under)

Neither has been ground beyond what the factory did. And, they are different housings. BDC's (Brian D. Cain) is showing a later FD iron and my picture is of a 12A iron. 

 

Lynn E. Hanover