From the Acaeum on Basic Set Printings:
Sixth (Nov-Dec 1979)
Blue box with a picture of a red dragon (artwork by Sutherland)
Wizard logo
Code in the upper right is "1001"
Angled yellow banner in upper left says "Basic Set With Introductory Module"
One of the following two combinations (and no, this makes no earthly sense):
48-page rulebook: Wizard logo, with "2001" in upper right. Inside says "Second Edition, Nov 1978". B2 Keep on the Borderlands (First print, no shrinkwrap)
OR
48-page rulebook: Wizard logo, with "2001" in upper right. Inside says "Third Edition, Dec 1979". B1 In Search of the Unknown (First print, no shrinkwrap)
Cardboard chit sheet attached to the rulebook, featuring dice chits, a "how-to-use" description, and a dice coupon
Bottom of box shows rulebook, neither dice nor chits, module B1 (even though some sets include B2), and has a Wizard logo
It is apparent that in this "transition" set (when TSR was switching between Second and Third Edition rulebooks, and between B1 and B2), that they played mix-and-match with remaining stock of rulebooks and modules
Seventh (Dec 1979)
Blue box with a picture of a red dragon (artwork by Sutherland)
Wizard logo
Code in the upper right is "1001"
Angled yellow banner in upper left says "Basic Set With Introductory Module"
48-page rulebook: Wizard logo, with "2001" in upper right. Inside says "Third Edition, Dec 1979". Two versions have been reported: one with an ISBN on the copyright page, and one without it
B2 Keep on the Borderlands (First or Second print (both have been reported), no shrinkwrap)
One of the following variations (listed in order of their appearance, but we didn't deem it significant enough to assign separate printings):
Dice chits with a "how-to-use" description and a dice coupon, all on one sheet and attached to the rulebook
Dice chits with a "how-to-use" description and a dice coupon, all on one sheet and unattached
Dice chits with a "how-to-use" description on one sheet, unattached
Dice chits and a "how-to-use" description on separate sheets, unattached
Five pre-colored dice in a small poly bag (no D10 or dice crayon)
Bottom of box shows rulebook, module B2 (pre-production print), and dice chits, and has a Wizard logo