Dave, I said tabs, to describe where the mounting hole is located. Probably wrong wording, but where the mounting hole is located on the motor, it is raised up a little, compared to other motors that look similar. Look at the photo closely, to understand what I called tabs.
I have to correct the above, after looking at a listing on eBay with both versions being auctioned. The stamped steel frame doesn’t have the holes in the side plates, like my Type 2 motor. The mounting holes on the steel frame that you have (original), the screw locations aren’t parallel, but one hole is raised higher in the body, than the other.
These stamped steel motors were pretty versatile, with changing wheels, type of E unit, headlight brackets, and things like that, you could find the basic frame on 1681, 258, 1688, 1684 locos. As you can probably guess, I’ve looked at 1000’s of photos of motors, for these locos from 1930-1940. I know basically what I can swap, in a pinch, with a little modification.