Just got thru replacing zone 1 pump, pretty easy, tight working position, just make sure you clamp the hoses real good, especially the horizontal one, don't ask me how I know
, it was suggested by the ITR tech to top the oasis off with fluid, via the radiator, and run it on by pass a few minutes with the cap lose to get rid of any air.
It is much easier access to pull the short tray out on the passenger side along with the slide tray beside it and crawl thru from the drivers side, and you don't have to empty any trays.
I got the pump from ITR and I believe it was $250