They all require phone calls... which may not be all that convenient for you, depending on your location and time. Even the Boson's Locker in Costa Mesa has limited phone hours... 8-4:30... and then they too recommended someone closer to me, which again meant phone calls during their hours. http://www.boatswainslocker.com/home/

Eventually I ordered parts from http://www.quivira-marine.com/store/ You can order online. Tried phoning a couple of times and it always sounded like I just woke someone up... "Huh, what?, Yeah?" But frankly the Quivira Marine website was lacking also... It was hard to tell if I was getting the right part numbers. Their hours and my hours just did not work... so I even had them ship it to me... just 10 miles away.

I got the Part Number data from this site:
http://shop.torresen.com/marine_diesel_direct/Yanmar/
They have a great website for finding parts... but they only ship to the East and Midwest. So they lost the sale, but were still used as a catalog. So you can at least verify part numbers and the like through them.

Apparently my engine was obtained from Mack Boring, as I have lots of their literature, including info on their prepackaged spares boxes. But I have had no contact with them.