The O-Ring on my 94 civic cx needed to be replaced. However when I pulled the distributor , I didn't see the old O-Ring on there. So I'm where it was. I've looked at the chilton's manual for this vehicle and It just has a picture showing the distributor , the distributor's coupling , the groove that in the camshaft the coupling goes in, and the O-Ring between them. And the book has printed by the O-Ring "new O-ring' or " O-Ring replace ". There is a flat part of the distributor shaft that doesn't spin the O-Ring could seat against. But on the other side of the O-Ring there is just the coupling which spins and the camshaft which also spins. So how would it stay in place and not be destroyed after the engine was restarted ?

There is only one spot for the o-ring to sit in.

Okay it sits directly beside the seal(touching it) doesn't it ?

"There is a flat part of the distributor shaft that doesn't spin the O-Ring could seat against." <--- your words earlier in this thread.
OK, listen closely... that flat part that doesn't spin.... that is the end of the distributor housing. You slide the o-ring up over that and further up the shaft until you see a groove, the ring goes in that groove. Its kind of like putting on a condom, sure you could just put it on the end but it would fall right off once you went to town, now the light comes on when you realise, hey what if I put it all the way on? GOOD LUCK