I'm wondering why you are swapping out a '55 first rear-end. Do you have a high horsepower engine in your truck? What are you replacing it with?
Will you want your front wheel pattern to match the rear? That will be a factor in determining how to go on the discs.
You should be able to easily sell your old rear-end to someone with a '53 or older. It's almost a direct bolt-up.
