Actually I found some for sale, but they just call them film holders with pressure plates. Are these the same or did Linhof make different ones?
Linhof made different styles, but as far as I know that will be the one. The other style is a "standard" film holder of supreme quality, with the added benefit of being screwed together so that it can be repaired (!). I'm trying to get hold of as many as possible of these, in 4x5" and 5x7"/13x18cm.
if you don't have a graflex slr, you probably don't want graflex film or plate holders. they are slotted to secure to the back of the camera, and they have a larger outside dimension than a "standard" / current film holder.
have you checked equinoxphotographic to see if they have 4x5 plate holders? sometimes they have things like that, and they have very reasonable prices