Thanks Whitedog, after a few trips to parts stores, I came home with the part. For future reference Felpro #55350 is the axle flange gasket.
I found the part stores that rely on computer programs to find parts is unreliable. It did take some searching in the parts books to find the right part. The book showed a pic and provided measurements for comparison, so problem solved. The store (with computer only) did try to help by ordering the wrong part for comparison. When that didn't work and after a two day wait wanted to order another part and delay me another three days with no idea that it would fit.
We have a Federated (Fisher Auto Parts) here and they have the old books and have been able to supply the parts (in stock) for the old bolt and at reasonable prices.