The Giants had planned to work out McGahee since last Friday, according to the source.
Jacobs, 31, spent his first seven seasons with the Giants before struggling through an injury-plagued season with the San Francisco 49ers in 2012. San Francisco waived Jacobs in December after the outspoken veteran was suspended for the final three regular-season games.
McGahee, who turns 32 next month, was released by the Denver Broncos this past June following a productive 2012 season that was cut short by a significant knee injury. Despite not participating in Denver’s voluntary offseason workouts, McGahee insisted that he had no physical restrictions when he was released.
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