These notes can be found in the forum thread for this set, but are worth repeating here as well:

1) The fourth quarter cards may never have been packaged, like the first three quarters, in a card board boxed and serial numbered fashion.

2) The fourth quarter may have been limited to just 500 non-serial numbered sets, unlike the first three quarters each being serial numbered to 3500.

3) Though these cards were considered to be available as an exclusive members only of the Hot Shots Emperor's Club, some of these cards may be found in Hot Shots 1997 Chronicles packs. The Emperor's Club seems to only have lasted one year, and I assume Hot Shots broke up the remaining unsold sets they had left in stock, but since the cards themselves are not serial numbered, it is hard to be certain.