Gah, I just put it away again! I will get the serial number tonight.
The disk and case were together originally, the motherboard I think I swapped with my main 6128, which is also in storage, somewhere else. I only have 3 6128 machines in total, and one of them is my original which is easily identified as it has a 40007 instead of a 40010, so I know it isn't that one!