I got my 62 3/4 ton, stepside. longbed back with a rebuilt, 30 over 235. It is running very well except that there is a vibration. I disconnected the fan belt, checked the points/timing/cylinder balance but the vibration is still there. It is a low-pitch noisy shake that is so pronounced it shakes my mirrors to much to read the license plate of the vehicle behind me. It is worse under a load. On the expressway at 55mph if I let up off the gas the vibration is greatly reduced. It vibrates even when stopped and is worse at specific rpm's so it is not the drive shaft. It had a slight vibration before it was rebuilt but nothing this pronounced. When they put the engine back together the harmonic balancer and associated pulley were different. I don't know about the fan blade. Also they made a mistake during reassembly and had to pull my trans and remove the clutch. Whether this has anything to do with the vibration I do not know. Any suggestions?
