According to Beckett,
"This five-card standard-size insert set was issued in honor of one of baseball's all-time greats, Joe DiMaggio. These cards were randomly inserted in first series packs. According to sources at Score, 30,000 of each card were produced. On a white card face, the fronts have vintage photos that have been colorized and accented by red, white, and blue border stripes. DiMaggio autographed 2,500 cards for this promotion. 2,495 of these cards were inserted in packs while the other five were used as prizes in a mail-in sweepstakes. The autographed cards are individually numbered out of 2,500."
So, sounds like the answer you're looking for is series I packs.