Humber is correct -- No. 50 is stamped on the end of the box. The outside dimensions of the box are 34L x 10W x 8 1/2H. My bottom tray (which looks like it may have been attached to the bottom) is pretty well shot, but I am hoping to patch up the bottom and one bad corner.
I will repost here when I sell it to let everyone know their value. I paid quite a bit for mine, so I am hoping one of my regulars who likes tap and die sets or someone at one of the tractor shows I go to will buy it.