So my completely stock 2005 Ram 2500 4x4 Quad Cab has developed a vibration between 60-65 mph. It is not the tires, as I balanced them and rotated them with no change. Trying to understand how to diagnose.

1) I went under the truck, and I cannot feel any free play at all when trying to move all the U-joints in the driveshafts. All I am doing is grabbing the axle with my hands near the joints and trying to move them - nothing. Not sure if that is the correct procedure....

2) It's a 4x4, and I have it set to 2WD. If I try to rotate the rear driveshaft with my hands, there is no movement at all. If I grab the front driveshaft, it will rotate a few degrees, so there is some play there. I wonder if that is normal, or because I have the transfer case in 2WD? Maybe if I put it in 4WD it goes away. Anyway - I do not know what is 'normal' here.

3) If I push up on the rear driveshaft, I can get some movement in the trans. I can see the trans lift in the trans mount area. Not sure how stiff that rubber mount is suppose to be, or if that is normal.

4) I have a one-piece rear drive shaft, so no intermediate bearing, which I read could be a source of vibration.


I know diagnosing a vibration is tough. I just don't know what is normal free play. I might remove the front drive shaft completely and see if vibration goes away.

THANKS for any knowledge!

Derek