Vibrating 2002 International 9400

I need help from you guys here. Last week I purchased a 2002 Int'l 9400. Cat C15, Eaton-Fuller 10 sp, Meritor 3.73 drives, 860,000 miles. I test drove this truck 50-60 miles bobtail. It runs great, and has no leaks. It drove smooth. When I put the first load on it, I noticed a vibration when accelerating through the gears. When truck is cruising on level or coasting, there is no vibration. But when it starst to pull a grade the vibration starts. The harder the pull, the more pronounced it is. When it is vibrating, I can feel it in the clutch free play, the shifter, and in the floor. When the power is leveled off, it goes away in these areas too. Has anyone else experienced this on an Int'l? Can you help with suggestion as what and where to look?

I read an old post here about the ride height. How do I determine the ride height? Is there a reference point to measure from; and what should the height be? Any and all responses will be greatly appreciated. Thanks

 

Mine is the one that the spring goes under the axle. I'm going out to check this now. Thanks for the help.

 

Ride height was correct. I carried it to a local shop. When I describe the vibration to the mechanic, his first though was pilot bushing. His next thought was trans mounts and u joints since clutch had been replaced by previous owner about 2 months ago. I left it with him he's going to test drive it, check it out to see if he can isolate it. He also has a flatbed loaded with big chunks of concrete to test with a load. If anyone has more suggestions, please pass them on, and I can relay them to him. He is a good mechanic who doesn't mind input. I sure hope he can find the problem. I really love this truck.

 

Thanks for the reply. What is HCV? I got it at the shop now. Mechanic said pretty much what you stated. He's going to check u joints, drive shaft, boxes for metal, engine and trans mounts. checking the obvious first, then moving to the more complicated items if problem is not found.

 

When you say sync the yokes, do you mean all yokes in the driveline must be at the same position?