I still have around 25 original Slim Jim holsters in my collection dating back to the California Gold Rush. None of these have the makers cartouche on the front. In fact, I personally, have never seen an original Slim Jim for a percussion or conversion revolver with the cartouche on the front. All of my maker marked originals have the makers stamp on the back, either above the belt loop or on the belt loop itself. On the other hand looped holsters for single actions are almost always marked on the front. I have also had a few Slim Jims that were made for single actions, that have the cartouche on the front. One of these is shown on the bottom of page 89 in the book "Packing Iron". The makers mark on this holster is stamped right over the cylinder area on the front. It reads "S.C.Gallup & Co., Dodge City, Kansas.
Buck