The most famous pre-Adidas World Cup ball of all time is the T-model from the 1930 Uruguay World Cup. Uruguay played the majority of its matches with this ball until they faced Argentina in the final match. Since Argentina wanted to play with their own ball (which was a regular 12 panel ball), the final was played with the Argentinean ball for the first half of the match, and the second half was played with the Uruguayan ball. The footballs may have had a significant influence, as Argentina took a 2-1 lead in the first half with their own ball, but Uruguay replied in the second half with their T-model ball to win 4–2, making them the first World Champions and the T-Model legendary.
Content courtesy of Worldcupballs.info