Brand new 2012 GMC diesel dually... bought to tow a gooseneck trailer. I broke it in gently for 10k miles. Then when I hooked up and loaded my gooseneck car hauler, it had a violent drivetrain vibration under heavy load. The dealer can't fix it! They say GMC is working on the problem! Meanwhile, the truck is useless for doing what it was designed for. I'm concerned it will rip itself apart. Should I pursue the lemon law on this one?