I think I may know the answer. I had a lp12 and tried a 103d years ago. Like 15-20 years ago. The Denon cartridge does have a large body, it's not the mounting into the screw holes, it's that the cartrige hook up pins extend back into the tonearm hookup pins. It's a bear to get the cartdige leads connected...it's almost like the cartridge pins and the tonearm pins are alomost touching...no room for the little wires.
Again, this isn't a conclusive answer...but a theory.
Again, this isn't a conclusive answer...but a theory.