I just was thinking while doing a search for O ring part #s that a part # stickey post might be useful, or even a sticky with just used items, say O rings, oil filter cross reference (Fram, Wix, NAPA), air filter, tires, even oils (JUST A LIST NOT A FLAME WAR) being used.
And perhaps add links where you found them.
Final drive O rings
http://www.carolinabikeandtrike.com/ORings.htm