I did some more looking into the direction of the rear shock mount. I can see no reason the lower mount can't be mounted in either direction. The dampening side of the mount is shaved from the outside to make room for the top of the bolt. The mount is centered to the shock rod and both sides of the mount are approx 12mm thick. I was looking at the mount earlier thinking the skinnier thickness of one side biased the mounting that direction but this is incorrect. Regardless of direction of the mount its centered where it is supposed to be either way.
I am gonna follow the parts diagram and mount the dampening controls to the left. That way all bolts are going the same direction. For some reason I think I read in a service manual for XT600s that mounting bolts should go in certain directions for different areas of a bike due to forces of energy created by engine torque causing bolts to loosen if mounted one way or another. Thing of it is all XT600 engine bolts are left to right and suspension right to left while KX500 is the opposite. Torque characteristics of 4T vs 2T? Then again maybe bolts just go the way they do because the assembly line at the factory is setup how it is? Maybe the dampening control was put to right over the years just to show the control in marketing pictures of the right side shock with its compression control too? I wonder what the engineers had in mind making the parts diagram show the dampening on the left? Bolt direction must have played a part as the 3d orientation of the diagram is pretty clearly marked with all bolts coming in from the left.
Dampening control is following parts diagram, facing left.