It's an intriguing question and one that seems to have its own logic for an answer. Jake is right, contacting them is the only real choice.
In the meantime, I'd add my own observations on this fine series. I really like the Black Box with red letters series which I believe ran from 1987 to approx 1992. A very large number of patterns were produced by Queen under contract. It is claimed that they used old Rogers Bone from 70 years before - so about the close of WW 1. Whether this is true or if it's some internet myth passed on I can't say. However, the bone and jigging is very beautiful on the few examples I have, really unlike anything around now or recently. My list is as follows:
2921-87 Coffin Jack
2857-87 Teardrop Jack
2851-88 Small Gunstock Jack
2903 - 90 Swell Centre Pen ( I use this one a great deal)
Three of them are 2 spring Jack knives, 1 is a single spring double end Pen. all have jigged bone. The last numbers are of course the year of manufacture.
3964 - 87 Stockman with small federal shield and satin finish blades
3971 -89 Swell Centre Whittler (another favourite of mine)
These are the three blade bone knives.
You could try contacting AL (Mad Merry Monk) he has possibly the entire collection and he very kindly gave me a Teardrop Jack as a present, for which I'm endlessly grateful. He certainly has a lot of knowledge of the series and might know the meaning of the tang numbers.
Thanks, Will