64nailhead gave a good suggestion. Check your tie rod ends, idler, and center link for wear. Sometimes, if they are not too worn out, you can pump the grease zirks full and that will tighten it a bit, but I wouldn't depend on that being a permanent solution, because if they are worn out, they will loose the new grease anyway.
I also agree about the series 800 pitman arm, the output shaft diameter is different between the 605 and the 800 type steering box.
I also agree about the series 800 pitman arm, the output shaft diameter is different between the 605 and the 800 type steering box.