The serial number on Ebonite balls is not relavent to how many are made.  The last four digits on an Ebonite ball serial number just mean what order it was packed that day.  In other words, we may only run 50 balls of a certain type but they could be numbered 0001 or 3650.  That doesn't mean we ran 3650 of them.  Only that one ball was packed first thing in the morning and one packed late that night.  The rest of the serial number is coded to represent other relevant info.

So far Ebonite has made 366 NV balls.  I just looked it up.