I don't believe that there were any mechanical changes between 52 and 53. Quite often GM only printed a supplement to the previous shop manual if there were only limited mechanical changes. The only cosmetic changes were that Stainless trim and chrome trim was either hard to get or non existent as far as actual 53 pieces went. I'd think that some forward thinking dealers stocked up on chrome grills, hubcaps and bumpers the day they found out that they were not available from the factory.
