I've had my new truck about a month now and everything seems fine. No complaints save one. There is a difinite and fairly loud HOWL in the driveline. It occurs at about 50 MPH just after the automatic transmission locks up and goes away between 55 & 60 MPH. I haven't been back to the dealer yet, waiting to see if I can find anymore problems. I checked both the transmission & differential fluid levels and both were down about a pint+. You'd think they would fill them properly at the factory. My question is of course, has anyone else noticed this or have any Ideas?