Roger Craig #33 runs with the ball push in the air after scoring a touchdown early in the first quarter against the Dallas cowboys in Candlestick Park, San Francisco on Monday, Dec. 20, 1983. Craig second two touchdowns in the 49ers 42-17 win that gave them the NGC west title. (AP Photo/Eric Risberg)

Dallas Cowboys head coach Tom Landry confers with his quarterback Roger Staubach (12) during the waning moments of NFC Championship game against San Francisco 49ers in Dallas, Texas, Jan. 3, 1972. The Cowboys won, 14-3, to face the AFC winner for the Super Bowl VI championship in New Orleans. (AP Photo)

49ers defensive end Cedrick Hardman (86) eyes Dallas Cowboys quarterback Roger Staubach (12) moments before sacking him for a loss in first quarter Dec 12, 1977 in San Francisco. (AP Photo)

San Francisco 49ers vs.Dallas Cowboys at Candlestick Park Sunday, January 10. 1982. 49ers beat Cowboys 28-27 for Conference Championship. San Francisco Wide Receiver Dwight Clark (87) celebrates touchdown. (AP Photo/Al Golub)

San Francisco 49ers quarterback Joe Montana (16) celebrates a 77-yard touchdown pass during an NFL football game against the Dallas Cowboys on Monday, Dec. 19, 1983, in San Francisco. The 49ers won the game, 42-17. (AP Photo/Greg Trott)

San Francisco 49ers vs.Dallas Cowboys at Candlestick Park Sunday, January 10. 1982. 49ers beat Cowboys 28-27 for Conference Championship. San Francisco Defensive End Jim Stuckey (79) blocks Dallas Cowboy Quarterback Danny White (11) from passing. (AP Photo/Al Golub)

San Francisco 49ers vs.Dallas Cowboys at Candlestick Park Sunday, January 10. 1982. 49ers beat Cowboys 28-27 for Conference Championship. Dallas Cowboys Running Back Tony Dorsett (33) finds hole in 49ers line to make yardage. (AP Photo/Al Golub)

San Francisco 49ers vs.Dallas Cowboys at Candlestick Park Sunday, January 10. 1982. 49ers beat Cowboys 28-27 for Conference Championship. Dallas Cowboys Running Back Tony Dorsett (33) reaches for pass with San Francisco Linebacker Keena Turner (58) in pursuit. (AP Photo/Al Golub)

Dallas Cowboys running back Tony Dorsett (33) scores a touchdown while San Francisco 49ers safety Dwight Hicks (22) gives chase during the NFL football game NFC Championship between the Dallas Cowboys and the San Francisco 49ers in San Francisco, California on January 10, 1982. The 49erswon the game 28-27. (AP Photo/Paul Spinelli)

San Francisco 49ers running back Ricky Watters (32) heads downfield during an NFL game against the Dallas Cowboys on Sunday, Jan. 17, 1993, in San Francisco. The Cowboys won the game, 30-20. (AP Photo/Greg Trott)

San Francisco 49ers offensive lineman Roy Foster (67) sits dejectedly on the bench and mud during the NFC Championship game against the Dallas Cowboys, Sunday, Jan. 17, 1993 in San Francisco. The Cowboys won the game, 30 to 20. (AP Photo/Greg Trott)

San Francisco 49ers vs. Dallas Cowboys at Candlestick Park Sunday, January 17,1993. Cowboys beat 49ers 30-20. 49ers defenders all tackle Dallas Cowboys running back Emmitt Smith (22). (AP Photo/Al Golub)

San Francisco 49ers' Tim Harris (99) reacts as the Dallas Cowboys' Kevin Williams (85) walks off the field after a 49ers first-quarter interception, Sunday, Jan. 15, 1995 at Candlestick Park in San Francisco. The interception lead to the second of three first-quarter touchdowns by the 49ers' in their NFC Championship game. (AP Photo/Paul Sakuma)

Dallas Cowboys quarterback Troy Aikman (8) scrambles for yards against the San Francisco 49ers' during the first quarter of the NFC championship game in Irving, Texas, Sunday, Jan. 23, 1994. (AP Photo/Linda Kaye)

Dallas Cowboys tight end Jay Novacek (84) catches a pass during an NFL game against the San Francisco 49ers on Sunday, Nov. 13, 1994, in San Francisco. The 49ers won the game, 21-14. (AP Photo/Greg Trott)

Dallas Cowboys' Emmitt Smith barrels through San Francisco's Rickey Jackson (57) and heads toward Deion Sanders (21), and the end zone, for his second-quarter, NFC Championship touchdown, Sunday, Jan. 15, 1995 at Candlestick Park in San Francisco. Smith re-injured his hamstring during fourth-quarter action and was taken from the field. (AP Photo/Susan Ragan)

San Francisco 49ers running back Kory Sheets goes over the top of the pile to score a touchdown in the second half of a preseason NFL football game against the Dallas Cowboys, Saturday, Aug. 29, 2009 in Arlington, Texas. Cowboys linebacker Steve Octavien (53) and center Matt Spanos (78) are shown at front. (AP Photo/LM Otero)

Dallas Cowboys Hall of Fame quarterback Roger Staubach (12) drops back to pass as tackle Tony Liscio (64) blocks San Francisco defensive end Cedric Hardman (86) during the 1971 NFC Championship Game against the San Francisco 49ers in Irving, Texas, Jan. 2, 1972. The Cowboys defeated the 49ers 14-3.. (AP Photo/Vernon Biever)

San Francisco 49ers tight end Vernon Davis (85) reaches up to grab a touchdown pass as Dallas Cowboys' Bruce Carter (54), J.J. Wilcox (27) and Justin Durant (52) watch in the first half of an NFL football game, Sunday, Sept. 7, 2014, in Arlington, Texas. San Francisco quarterback Colin Kaepernick threw two touchdown passes to Vernon Davis, one right after the first of three interceptions by Tony Romo, and the 49ers opened the season with a 28-17 win over the sloppy Cowboys on Sunday. (AP Photo/LM Otero)

Dallas Cowboys Hall of Fame running back Tony Dorsett (33) runs upfield during an NFL game against San Francisco 49ers in San Francisco, Sept. 9, 1979. The Cowboys defeated the 49ers 21-13. (AP Photo/Arthur Anderson)

San Francisco 49ers nose tackle Mike Purcell (64) returns an interception for a touchdown against the Dallas Cowboys during the first half of an NFL preseason football game in Santa Clara, Calif., Sunday, Aug. 23, 2015. (AP Photo/Tony Avelar)

Dallas Cowboys quarterback Tony Romo (9) during the NFL regular season game between the San Francisco 49ers on Sunday Sept. 18, 2011 in San Francisco, Calif. (AP Photo/Ric Tapia)

Dallas Cowboys running back DeMarco Murray (29) runs past San Francisco 49ers linebacker Aaron Lynch (59) during an NFL football game Sunday, Sept. 7, 2014, in Arlington, Texas. (AP Photo/Tony Gutierrez)

San Francisco 49ers Hall of Fame quarterback Joe Montana (16) turns to handoff during the 1981 NFC Championship NFL game against the Dallas Cowboys in San Francisco, on January 10, 1982. The 49ers defeated the Cowboys 28-27. (AP Photo/Arthur Anderson)

San Francisco 49ers vs. Dallas Cowboys at Candlestick Park Sunday, January 15, 1995. 49ers beat Cowboys 38-28. San Francisco 49ers full back William Floyd (40) touchdown. (AP Photo/Al Golub)

San Francisco 49ers vs. Dallas Cowboys at Candlestick Park Sunday, November 10, 1996. Cowboys beat 49ers 20-17. Dallas Cowboys running back Emmitt Smith (22). (AP Photo/Al Golub)

San Francisco 49ers' running back Frank Gore (21) runs as guard Jonathan Goodwin (59) blocks Dallas Cowboys' linebacker Keith Brooking (51) in an NFL football game in San Francisco, Sunday, Sept. 18, 2011. (AP Photo/Marcio Jose Sanchez)

Dallas Cowboys quarterback Tony Romo, left, greets San Francisco 49ers quarterback Colin Kaepernick after an NFL preseason football game in Santa Clara, Calif., Sunday, Aug. 23, 2015. (AP Photo/Ben Margot)

San Francisco 49ers offense lines up against the Dallas Cowboys defense during an NFL preseason game against the Dallas Cowboys at Levi's Stadium on August 23, 2015. The 49ers defeated the Cowboys 23-6. (Kevin Terrell via AP)

Dallas Cowboys Hall of Fame running back Tony Dorsett (33) is wrapped up during an NFL game against the San Francisco 49ers in San Francisco, Sept. 9, 1979. The Cowboys defeated the 49ers 21-13. (AP Photo/Arthur Anderson)

Dallas Cowboys rookie tight end Geoff Swaim (87) catches a pass during an NFL preseason game against the San Francisco 49ers at Levi's Stadium on August 23, 2015. The 49ers defeated the Cowboys 23-6. (Kevin Terrell via AP)

Dallas Cowboys quarterback Tony Romo (9) lines up with his teammates against the San Francisco 49ers during the second half of an NFL football game Sunday, Sept. 7, 2014, in Arlington, Texas. (AP Photo/LM Otero)

Dallas Cowboys defender Deion Sanders (21) knocks the ball away from San Francisco 49ers receiver Jerry Rice (80) in the second quarter in Irving, Texas, Sunday, Nov. 12, 1995. (AP Photo/Eric Gay)