The 49ers must have been a pretty good team back in the early 1970s, since Topps had designated 3 of their players as All-Stars (including the QB).
A quick check of Pro-Football-Reference.com shows that they were just coming off a 1970 season where they finished 1st in the NFC West, with a 10-3-1 record (the 2nd best record in the NFC after Minnesota). They lost the NFC Championship game to the Cowboys.
In 1971, they slipped to 9-5, but still finished 1st in the division. In both seasons, they were 1 win ahead of the Rams.
#100 John Brodie - Brodie's rookie season in San Francisco was 1957. In 1970, he was the league's MVP and leading passer. His last season as a fulltime starter was 1971, as he shared the QB job with Steve Spurrier in 1972 & 1973.
#129 Ken Willard - This card tells us that Willard led the 49ers in rushing for each of his 1st 6 seasons (1965-70). After 9 seasons as a 49ers regular, Ken finished his career as a bit player with the Cardinals in 1974.
#165 Gene Washington - Gene was an instant sensation from his rookie season in 1969. In 1970, he led the league with 1100 receiving yards. Washington was the 49ers' star receiver for 9 years, then missed the 1978 season. In 1979, he finished his career with the Lions.
#52 Cas Banaszek - Banaszek played his entire career (1967-77) with the 49ers. He was drafted as a linebacker, and switched to tackle in his 2nd season. Cas was the 49ers' starting right tackle for the remainder of his career.
#77 Bruce Gossett - The only player in this set that didn't begin his career with San Francisco, Gossett played 6 seasons with the Rams before moving to the 49ers in 1970. He led the league in scoring in 1966. Bruce finished his career with the 49ers in 1974.
#149 Cedric Hardman - Cedric played 10 seasons with the 49ers (1970-79) before hopping across the bay to Oakland for 2 more seasons. He played in 2 Pro Bowls.
#213 Charlie Krueger - When I got this card in 1971, I thought Krueger looked like somebody's grandpa, but he was only 36 at the time. Charlie didn't play during his rookie season of 1958, but he was a fixture on the 49ers' defensive line from 1959 through 1973. After a few seasons at defensive end, he was the 49ers' starting left defensive tackle for the rest of his career. This is one of the few lineman's cards with a statistics chart on the back, thanks to an interception in 1969.
#189 Dave Wilcox - Dave was the 49ers' starting left linebacker for 11 seasons (1964-74). He was inducted into the Hall of Fame in 2000. (I always thought he looked like Gilligan on this card.)
#24 Jim Johnson - The 49ers' 1st draft pick in 1961, Johnson played 16 seasons (starting at left cornerback from 1964-76) until his retirement following the 1976 season. He was inducted into the Hall of Fame in 1994. He is the brother of former Olympic track star Rafer Johnson.
#239 Bruce Taylor - San Francisco's other cornerback was a first round pick in 1970. He played 8 seasons, all with the 49ers. For most of his career, he was also the team's punt returner.
Also check out the 1967 and 1972 49ers.