The San Francisco 49ers will have their entire defense returning next season, but the team made several moves Thursday to give it a different look in 2012.
The 49ers released cornerback Shawntae Spencer on Thursday after he spent eight seasons with the team.
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Later in the day, the 49ers agreed to terms on a one-year deal with special teams standout and backup running back Rock Cartwright, a league source told NFL Network insider Jason La Canfora.
Cartwright, who played the past two seasons with the Oakland Raiders, should help fill a void after Blake Costanzo signed a two-year contract with the Chicago Bears on Tuesday.
La Canfora also reported Thursday that free agent wide receiver Mario Manningham and former 49ers wideout Brandon Lloyd visited team headquarters. Chaz Schilens also met with the team Wednesday.
The 49ers continue to seek options at wide receiver after signing Randy Moss and losing Josh Morgan to the Washington Redskins.
The 25-year-old Manningham had 39 catches for 523 yards and four touchdowns last season, his fourth in the NFL, while playing behind Hakeem Nicks and Victor Cruz. Lloyd, who played three seasons for San Francisco from 2003-05, made 70 receptions for 966 yards and five touchdowns in 11 games for St. Louis last season.
The Associated Press contributed to this report.