I recently sent out my front and rear differential housings for powder coat, made a rookie error and forgot to note which was which. When I put them side by side, I cannot tell the difference between the two, aside from a few numbers on the outside. One has a marking of a 7 in one spot and the other has a 9 in the same location. Both have a 'D' in another location. In a 3rd location, one has a '-60011' and the other has a '41111-60011'. Pictures below. Does anyone know how to tell which is the front and which is the rear?