I found some interesting information. You can make of it what you will.

These are selected years followed by the Fortune 500 ranking that year.

1955 141
1956 75 (the best during this period!)
1963 141
1964 138
1965 233
1966 325
1967 382

Studebaker-Worthington also had rankings that differed and during the same years. I have not figured that one out. Here are some later S-W rankings:

1968 118
1969 140
1970 141
1979 196