Vibration between 32-42 mph.
I cannot figure out what this is. It does not occur until 32 mph, vibrates the whole truck until around 42 mph. At around 40, if I let off the pedal, it goes away for a moment, but comes back if I keep the pedal steady. At highway speeds, it is smooth as can be. I have replaced the u joints, greased the slip joints, and replaced the carrier bearing. I am assuming it is in the driveline, but sometimes it feels as though it is coming from the front left wheel, but I am not sure how that could be, as it stops sometimes when I let off the pedal.