It's a long story.
I broke the groundglass element of my Hasselblad "Groundglasss focusing adapter". Don't ask how. The fresnel is fine. I cannot find a source of glass .065" thick. The groundglass is NLA from Hasselblad.
The 2 4x5 glass plates I have are .058 (approx) thick. So the expediant solution seems to be to use the glass to have it ground and sized to fit. I can make some shims to make up the thickness difference.
Thanks for the ideas.