http://www.rockauto.com/catalog/raframecatalog.php
I'm not sure what the differences are but I used one for a 69 C10 and it works fine. I know they have a close ratio one too. I believe 77 and up have metric hose fittings, which means your power steering pump would have to match.
I bought mine from the above link. It's $124.99 plus $75. core charge for one from A1Cardone, which is the one I used. I bought parts from different part sources but in hindsight I would have been better off buying a complete kit. I think it cost me more doing it this way, but I'm very pleased with the outcome. Brothers sells the complete kit too.
Joe

Last edited by cal55; 02/28/2009 5:53 PM.
54 Triumph TR2(rhd)needs total resto.
60 Apache 10 stepside shortbed
99 Excelsior Henderson