A friend and I have been trying to make some complete Gray wrench sets. Didn't even know if the 6mm existed in the 'gray alloy canada', but it actually turned up in a random toolbox buy. Getting closer to a full metric and standard set.
I'd really like to hammer down the years they made the changes to the three different handle styles. I also noticed that they changed the size of the upper boxes at some point by half an inch (during second model), so that the top drawers and bottom drawers would be interchangeable.