Let's see what my GM service manual says.......
Well, after checking out some pages in the manual, it reads like this:
"During the installation of a body mount, caution should be used to insure that the body mount is properly seated in the frame mounting hole, otherwise a direct metal to metal contact will result between the frame and body. The tube spacer should be in all bolt-in body mounts and the insulator or metal washer positioned to prevent contact with the frame side rail. Do not over-torque the body mount or a stripped bolt may result.
Do not use lubricants of any kind on the rubber parts of the mounts. Proper clamping by the mount depends on clean and dry surfaces. If the body mount bolt does not screw in smoothly , it maybe a necessary to run a tap through the cage nut in the body to insure that tap doesn't punch through underbody."
So, it sounds like tighten it to where the rubber does not collapse but firm enough to hold the body to the frame. /forums/images/graemlins/thinking.gif