Main problem w/ body lifts is you stretch everything to the limit and you CAUSE problems. Also the motor stays in the frame while the intercooler moves up so you will need to do soemthing about that. Also, correct me if I'm wrong but doesn't a 5th wheel bolt thru the bed to the frame or crossmember parts? If so, you'd be putting space between the bed and frame and you'd likely be adding stress to the bolts that hold it in higher then their capacity and will likely rip something up!