I checked the front wheel bearings today. They castle nuts were snug. I couldn't tighten them up to the next notch without really reefing on the nuts with a socket and breaker bar, so I left them as they were. There was no slop or play in the front wheels, side to side or back to back.
This intermittent grumble comes with a significant vibration in the truck. However, I don't feel the vibration in the steering wheel or stick shift. It is more a general vibration through the whole truck.
I will check the u-joints next but inspection of them a few months ago show no signs of wear or play.
The transmission shifts fine with or without the vibration. Steering is fine, brakes work great. Nothing seems loose underneath like the driveline mounts or anything else. What would cause the truck to vibrate like this intermittently in any gear or neutral, at any speed, and it comes and goes just like the wind. The truck does have to be rolling though. One more clue, the vibration doesn't increase or decrease when the car slows down. It stays constant in noise and vibration right up until the truck comes to a complete stop, and then the vibration/noise stops suddenly, almost as if on a switch.
James
