In March 1967, the Eagles traded Gros,
guard Bruce Van Dyke and a 1967 third round draft pick to the Pittsburgh Steelers for receiver
Gary Ballman. The Steelers used the draft pick on center
Rockne Freitas. The Steelers had been the NFL's worst rushing team in 1966, and the trade was part of Coach
Bill Austin's plan to remedy that situation. Austin had been one of Gros's coaches in Green Bay, and he considered Gros the best blocking fullback in the NFL. Gros suffered a knee injury in 1967. He played in only 12 games for the Steelers, starting just seven. He had 252 yards in 72 rushing attempts with one touchdown. He also had 19 receptions for 175 yards. Gros came back in 1968 to start 13 games for the Steelers. He gained 579 rushing yards (second most in a season during his career) in 151 attempts. He had three rushing touchdowns. Gros also had 27 receptions for 211 yards and three receiving touchdowns. His six total touchdowns were second on the team to receiver
Roy Jefferson's 11. Gros started 11 games for the Steelers in 1969, gaining 343 yards on 116 carries, with four rushing touchdowns. He added 17 receptions for 131 yards and three receiving touchdowns. His seven total touchdowns were again second to Jefferson, who had nine. In early September 1970, the Steelers traded Gros to his home state
New Orleans Saints for an undisclosed 1971 draft choice. He played in the Saints first game on September 20, 1970, with two yards in four attempts. The Saints waived Gros the next day, ending his NFL career. He finished his career with 821 rushes for 3,157 yards (3.8 yards per carry) and 28 touchdowns; he also had 142 receptions for 1,255 yards (8.8 yards per reception) and ten touchdowns. ==NFL career statistics==