Labonte, the 2000 Cup champion, signed a four-year contract extension with Richard Petty's organization earlier this year when Boston Ventures purchased a majority interest in the famed team.

However, faced with an unsponsored car for next season, as General Mills left for Richard Childress Racing, and Petty currently in negotiations with Gillett Evernham Motorsports to merge, Labonte and Petty have mutually agreed to end their relationship.

"In over 15 years of racing in the Sprint Cup Series, I can't remember a time when the sport's landscape looks as it does today," Labonte said in a statement. "Saying that, Petty Enterprises and I had serious and very sincere discussions about what was best for myself and everyone involved at Petty Enterprises moving forward. These discussions culminated with us agreeing that moving in a separate direction will be the greatest way to reach our end goals. It was by no means an easy decision."

Labonte has recorded 21 career victories, but has not won a Cup race since the 2003 season-finale at Homestead. He came on board with Petty in 2006 after spending 11 years with Joe Gibbs Racing.

Labonte's plans for 2009 are not set at this time, but one likely scenario has him driving the No.41 car at Earnhardt-Ganassi Racing.

"Moving forward, I'm very anxious to prepare for the 2009 season," Labonte said. "I do not currently have a contract with any other team for 2009, but I am ready to explore all opportunities and form the next partnership in my career. I'll continue to keep these matters private and will make the appropriate announcement and comments when my future plans are confirmed."