Since I'm not having much luck finding a Grafmatic I thought I'd try for some Graflex 4X5 film holders. The kind with the grooves along the edges to fit Graflex reflex cameras.
Check the flickr forum for Graflex or Speed Graphic. I think some poor fellow purchased some of the holders inadvertantely and found them unusable with his camera. The discussion was only a month or so old.
Another member had expressed interest in them but I do not know how it turned out. He may still be stuck with them.