I'm pretty sure Steve is pulling those numbers out of his ass as "opinion" as I see little reason they would produce 6,000 more HuCards than manuals. Not to mention 8,000 was way too high for such a late game.
3,000 is probably in the closer ballpark. Most of the end-of-life games had runs in that general vincinity, while some only got 1,500 copies pressed (Dynastic Hero, etc). This comes from a guy I know that used to work for Hudson.