I rebuild my own pumps just like Ford built them except I use the double lip seal in the rear bushing. So, no, in my case no way to tell the difference.
Actually when I rebuilt it totally as original it was also leakless. I used 2 lead packing rings with Mystik Jt-6 red high temp grease, and in 15 years of driving, it never leaked a drop. I only took it apart and installed the double lip seal to better ensure the antifreeze and grease stay on their respective sides of the seal.