Well if you go to a manual box the pitman arms swap. The manual and 600 boxes have the smaller pitman shaft diameter. The 800 uses a larger shaft. As for leaking, mine had lots of pitting on the shaft which is why it leaked and when I went for the shaft seal kit the guy said they all will leak. Even with polishing the shaft it still leaked so I went with an 800 box. I noticed no difference in the steering effort between the two.