Yeah, this is pretty old Gerber, RS274-D format, with separate aperture files. Most viewers won't take this, and most PCB manufacturers won't care either. You could re-create the aperture definitions for each file (associated .rep) and add them in the corresponding Gerber files to make them compliant (RS274-X), but that would be some work (and you need to know about Gerber...)
Sorry I don't have PADS...