I have to be honest, I don't feel you will find the procedure. All my resources only go back to 1974 which stopps me dead in my tracks. As far as a recommendation, I have to say you need to go to a book store and see if they can order a manual specific to your vehicle. I have to warn you, many of the "general" manuals will not have the info you need, so make sure the store will return it if it doesn't supply the needed info. One other idea is to contact a dealer to see if they have an old manual that they could lend you.
I wish I had a better answer, but when you go back that far, things get difficult to find.