Thats what a track bar is...the "side to side" link is a panhard bar. Do a search on trackbars and look here:
http://board.marlincrawler.com/index.php?topic=7088.0How much frame do you have left...you can move the mount back as far as possible and run a longer shackle. Or yo could pin the second shackle to the frame so it can't drop open.