Drivetrain harmonics

[Gpenntx]

2001 Quad Cab, 24 valve, 4 speed auto (47RE) I think. Truck has 204K and drives fine but has a fairly loud harmonics in the drivetrain between 50 and 60 mph. Original trans and u-joints. Trans serviced yearly. Anyone have a similar experience and found the cause?

 

[JR]

If you can change the harmonics for better or worse by throttle input I'd suspect drive line. At that mileage and age universal joints and carrier bearing would be highly suspect and worthy of a good inspection if you haven't done so recently. Driveshaft must be removed to properly check u joints. If you drop the driveshaft make sure you mark the pair with a paint stick or something similar before removal to ensure proper phasing on reassembly.

 

[NIsaacs]

Is it long or short bed, 4x2 or 4x4? When was the last time for rear axle service? Is it open diff or limited slip? If it is open, I would suspect the left carrier bearing, the D-70 open diff is bad about that. If you haven't pulled the cover lately I would do that and see if you have any shim material on the magnet.