The majority of the gt guys here, not sure with v6 but I would imaging the same, will tell you that our rear axles weren't centered from the factory. Its pretty easy to tell when you're breaking loose.
That said, I would say go for it. You dont have anything to lose. Maybe some increased nvh. Plus the oem one doubles as a rain stick.
2013 5.0 - Deep Impact Blue
Brembo, GT500 axle backs, Vogtland springs, GT500 shocks/struts, Laguna SECA transmission scoop, 3.31, Carbotech xp10/8, JLT brake ducts
TWS CCW: 2:03.02