Quote Originally Posted by Satinsnow
Normally ground glass thickness is not criticle, unless you have a mount that requires the screen be slid into a slot, as long as the ground side of the screen is in the correct registration for the film plane, you should have no problems at all, the most important thing is to make sure the ground side of the glass is in the proper orientation of where the film in located in the holder.

Dave
... or as I learned, if your camera has a fresnel lens in front of the existing ground glass then you will still have to use that fresnel lens with a new ground glass or you won't be able to get a sharp image on your negative.