Duane, I've replaced that o-ring on the red bike. Perhaps I didn't think about it enough to recognize a problem. But grabbed a ring out of a viton assortment tray. Just visually matched it up and used it.
I didn't think about it either until I got a little rammy one day reconnecting the fuel line. Had a bit of a leak. Pulled the o-ring and it was shredded on one side.
Went to the dealer, not available. Had to buy the $45 or so tank fitting.
I tried several Viton o-rings, never found a match. But maybe I was trying too hard to get an exact size copy.
For the price of o-rings, I'd buy dozens and give them away if I could find the right one. I think the last batch I bought was like $10
Shouldn't be a problem just being careful with the fuel line. I most likely had it cocked to one side without realizing it.