Okay, I learned that it's about tightening it enough so that the shock does not move front to back (the parallel mounts should not be stressed by tightening together) which is held in place with the metal tube spacer located in the shock bushings. They need to be loose enough to allow play as arm moves up and down during driving. So... it's not about torque but about letting lock nut and spacer washer hold that bolt in place.
