One other thing to watch out for that's a difference in the axles, the drag link arm is different on the '55 that what is on '56-'59. They used an insert piece on the bottom when the stud on the drag link connects, it's not unusual to see that missing. The Pitman arm is the same way. The drag link will work without the insert, but you will need to add a thick washer for the nut to seat on, otherwise it will try to suck down in the hole. Alternatively, you can swap the arm from the old axle.

Bill Burmeister