I have a 2004.5 auto with about 302k on it. I’ve noticed that when cruising or under load at low speed, there is a terrible vibration that is felt in the cab, mostly the accelerator pedal and dash when I let off at about half throttle. It doesn’t feel like tire vibration as it’s not shaking the wheel and my tires are brand new with about 6k on them. I have a feeling that it’s the harmonic dampener as it feels like when the truck is cruising with throttle there is no vibration, as well as when i’m completely off the throttle, just when im half throttle under load above 55. any ideas would help greatly.

 

As you indicated maybe the harmonic balancer or perhaps u joints or carrier bearing. Not sure if it has a carrier bearing. Maybe flex plate or torque converter?

47

 

no carrier bearing, torque converter wouldn’t make sense when it’s not locked and the flex plate hasn’t given me any issues before. i’m thinking either u joints or harmonic dampener. gonna rip the front driveshaft off and inspect it then go for a drive to see if it’s u joints. I have a feeling it’s definitely front end related.

 

Check U-joints, carrier bearing, and harmonic balancer for issues.