[C320-list] Sea Water Pump E Eng.

[swampcreek42]

After changing the fuel filters and bleeding the system we started the engine and checked for leaks, the diesel system was fine BUT I discovered the sea water pump is leaking at the bushing, I'll rebuild this later for a spare. Right now I'm buying a new one, for post 1996 or 1997 Yanmars the engine has an "E" at the beginning of the serial number, in looking for a new pump I find 1 that's around $240 and one that's around $500. After going to the boat and looking at the serial number on mine I found that it is luckily the lesser expensive of the 2. My question is what the heck is that more expensive one for? Why would there be 2 different pumps for the same model years?
Bruce Hunter Nauti Time #719