$ SOLD - but no 'pm' please, contact me directly via email at; AJSERRANO @ MSN dot COM - Thx!~ 
BTW, no I'm not going crazy... I know these early Magnesium parts no longer show up, not in this condition, not anymore. I've looked over the last few years and can't seem to find them. If they do come up for sale, most of the time the Magnesium area for the large O-ring is usually corroded away and someone has tried to repair it. Incidentally, the part was painted and probably the reason why it survived this long intact.
You can't never pay too much, but you can certainly buy them too early.
More
photos here
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1970 Porsche 914/6 GT > Recreation in progress...
http://www.pbase.com/9146gt/my9146gt
1970 Porsche 914/6 > Crashed, driving while sleeping (not good!)
1974 Porsche 911 Carrera > Stolen, recovered in pieces