2002 Bonneville SLE

I changed plugs today and found a small gas leak on the quick-connect fuel line (that connects to fuel rail) So I pulled it off and removed to two Viton o-rings... but dropped the yellow one somewhere in the engine bay!

I have no idea what size it was! Does anybody have any idea? I bought a multi-viton pack... found a match for the orange one. Stupid me even forgot which size went in the furthest and nearest the opening... argh!