Look what i did this last week for my old m715 !!! . i rebuilt my m715 water pump. it was a little hard to dissasemble it and not damage any of the 42 yr old main components like the pulley, aluminum housing and the super tough to get off impeller... good thing i have most h/d shop tools at my dissposal cauz it took some doing. had to machine the seal surface of the impeller as the old seal had worn groves in it and i didnt want it to eat up the new seal prematurely. took me about 7 hrs from start to finish. what do you think ? heres a picture of blacky that it came off of and is going back on . the original engine is still in it and its got 49k miles on it. i never drive it over 45 mph is why its lasted so long. on the w/p i always run 1" of in & out belt play and 75% antifreeze mix. this keeps the pump well lubed & no belt tension over stress.