We just lucked into the knowledge. When an examination of a pump we had in*for a leaking seal/worn shaft showed that the shaft of the Lehman*drive coupler was cracked and was well on its way to a sudden failure, the recommendation of our diesel shop was to change both engines to Johnson pumps. As it turned out, the 3/4" pumps were back ordered, but the shop we use (and American Diesel who they get their pumps from) said that we could go with the 1" pumps instead, which had the advantage of the higher flow volume.
Where I noticed this in particular was the temperatures of the transmissions. The engine temps on the gauges was unchanged, but the "by feel" temperatures on the transmissions were noticeably lower. They never ran so hot that you couldn't comfortably keep your hand on them but with the 1" pumps they ran noticably cooler, which with a tranmission is always a good thing, I think.
-- Edited by Marin on Tuesday 25th of May 2010 01:40:59 AM