And Martin Mayhew's slick dealing continues.
Detroit also gave the Seahawks its fifth-round pick in April's NFL draft.
The move instantly solidifies Detroit's strong side linebacker position, which played musical chairs to a small army of projects in 2008. The instability opposite the weakside position dampened the play of Ernie Sims, who struggled mightily last season.
As a whole, the Lions linebacking core last year was horrendous, making the pick-up of Peterson one of Mayhew's most successful trade ventures to date.
According to FOXSports.com's Alex Marvez, Redding agreed to restructure his contract to help seal the deal.
A third-round pick out of Texas in 2003, Redding tallied just one sack in 2007, leading the team with three last year. After a stand out "contract year" in 2006, Redding never responded appropriately on the field to a $49 million deal inked in 2007. He drew the ire of the media and fanbase with his lack of productivity, which never seemed to match his talk.
Peterson, meanwhile, managed a Pro Bowl berth in 2008 despite a drop in production. The former Michigan State standout registered five sacks last season, half of what he accrued in 2006 and 2007, respectively. Peterson also forced four fumbles, however.
The only drawback might be Peterson's age. He turns 31 in July, and is entering his 10th year in the league.
The Lions are expected to run the 4-3 defense in 2009, but the acquisition of Peterson could potentially change that. While it's likely they'll stick with 4-3 (and still require a middle linebacker via the draft), a 3-4 would require less defensive linemen, and take advantage of Peterson and Cliff Avril on the outside, with Sims and Dizon patrolling the inside.
Detroit's defensive coordinator, Gunther Cunningham, enjoyed some of his most effective defenses in Kansas City employing the 3-4.