Hellwig makes a retrofit kit with sway bars, overload springs and air bags for the Greyhawk if your rig didn't come with the J-Ride package. The J-Ride package includes, BILSTEIN shocks, MorRide isolation dampeners, Hellwig overload springs, Hellwig rear sway bar.
I plan on adding a front Hellwig sway bar.
2004 Chevrolet Silverado 3500 LT with a 2004 Jayco JayFlight 29BHS
2014 Greyhawk 31FS with a 2007 Tahoe toad
2014 Thor Palazzo 33.3 with a 2007 Tahoe toad