1998 GMC K3500 7.4L vibration

[Mark Ruset]

I recall a GM service bulletin that addressed engine vibrations, It had to do with adding a shim type spacer between the block and mount. I believe the issue had to do with alignment of the motor mounts. I don't recall what years it was related to. On another note make sure that the motor mount bolts going into the block are not bottoming out before the mount is completely tightened,