Alero Intake manifold replacement

I just replace the dredded Alero Intake Manifold Gasket but I lost the o ring on the fuel pressure regulator and it started leaking gas I can seem to find the o ring and I dont even know it it requires one
Please advice where to get them

Best to try the local GM dealer parts department. There is an o-ring at the part where the fuel pressure regulator inserts into the fuel rail. Without the o-ring fuel will leak out onto the engine which could pose a safety hazard by starting an engine fire.