You've struck a nerve with your question and I just realized how dumbed down this country has become. This is supposed to be the information age, but it seems to me it's the anti-information age.

When I was younger and building this and that, there was a progressive size chart available from this place or that where you could choose the size part you wanted and find a part number beside it. In particular, I remember such a chart that I had from Chicago Rawhide, a huge seal manufacturer. They sold out to SKF several years ago and now you have to have the make, model and year of the vehicle to source a part. BALONEY. Pi**es me off.

I do believe however, that your local NAPA store will still have paper books that have progressive size charts. I know the local guy did this for me a while back when I needed a particular size O-ring seal.