I purchased it for a GMT II. Let me know if Preik responds. I think his spam filter is blocking messages as he seems that his email has fallen into the ether, although his brick-and-mortar store exists.

FWIW, I show how to install the caseback at http://www.minus4plus6.com/caseback.htm and on YouTube at http://www.youtube.com/v/7mj2CYnmt5Q&rel=1

-Sheldon