I don't know about the oil pump but unless you get OEM Mitsu for a H2O pump I'd go to Napa and get their rebuilt for $60. Most aftermarket H2O pumps don't have the "key" helps you center the P/S pulley & alternator pulley on to it, the Napa one does though.
Heres one from Kragen that doesn't have the key on the waterpump to align the pulley's...
This is the one from Napa that had the post (key) on it to get them centered on it. It's not necessary but it saves A LOT of install time whenever your trying to get the pulley's back on it.
