I don't know if you run biodiesel or WVO, but I figured out the size of the o-ring that goes on the tank strainer. I bought a couple of packs of them in Viton and have the individual o-rings on my site.
http://www.fryerpower.com/store/page11.html

If you run biodiesel/WVO you might as well put in an o-ring that will stand up to them.

-Jim

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.