Power to manual box conversion on 1968 Dodge Dart

First I heard that the Pitman arm varies between power and manual gears in the same year. The gears and Pitman arms did change in 1973 to the larger diameter output shaft (that B,C,E bodies always used), so insure you didn't get a 1973+ manual gear (won't work). The linkage changed also, with the Pitman and idler ball-joint shafts pointing down (so easy to tell). I recall someone saying manual gears kept the small shaft 1973+, but I think that was disclaimed.