IANAP (I am not a Professional) but I just finished having two natural casing Nathan’s franks for lunch that I grilled in an ordinary consumer electric fry pan. They were superb, as usual. You may want to look at this page on the Nathan’s web site about their Branded Product Program:
http://www.nathansfamous.com/nathans/business/htmls/branded_product_program_main.php
I have not heard of Nathan’s selling food service packs of their franks unless they have some sort of sales agreement in place. But, they have some sort of distribution network in place to sell foodservice products nationally.

I bought my natural casing franks on special at a supermarket- two packs for $4.99. These retail packs have six franks in each package.