I recently bought a 1988 K75S. Great motorcycle. I have a line on a pair of used hard cases for it, but I don't know for sure if they will fit my machine. They came off of a K-100. The photographs show the protrusion at the bottom front of each case that appears to fit into the mounting hole directly in front of the passenger footpeg. Can anyone say for certain that these cases will fit my K-75S? My motorcycle already has the hard plastic mounting rails. I just don't know enough about the cases themselves to spend the money through the mail. Is there a part number somewhere on the cases that will pin them down? Help!