I just took a valve to Napa and told the inexperienced counter jockey to go find me some that fit. I thought that he would never leave the security of the all-knowing computer to go scrounging for me, but he eventually did. I dearly miss the 'old' Napa stores where they employed people who knew more than i do. Now they are all to eager to tell you that "they don't carry that part", just to make you leave.
Carl