Who was the last Chicago Cub to hit 40 home runs in a season before Sammy Sosa?

The last Cub to hit 40 home runs in a season before Sammy Sosa was Ryne Sandberg, who hit exactly 40 in 1990. He batted .306 that season, with 100 RBI, and 25 stolen bases, and finished fourth in the National League MVP voting.