[greg64]

I've mucked around with these boxes in the past. The boxes will interchange, no problem. The power box has an extra bolt holding it to the frame. The pitman arms are different. The fittings for the hoses change around 80. The early fittings are flared and the later "metric" fittings have an o-ring. The fitting in the back of the pump can be changed from old to new or new to old fittings.