AFAIK, there are only 2 versions of the instrument case: the 750 shorter unfinished alloy one 06-0510, and the taller 850 part 06-4144.
They are, I believe, both aluminum and the 850 appears to be anodized, not painted, so it's gonna be quite a job to get below the anodized layer. I quit before I got very far with such an effort, preferring the shorter parts anyway. Still don't understand the logic of making them longer and heavier for the 850.