James Earl Jones being added to the credits.
Edit: I should also mention the “A New Hope” crawl, even though it technically wasn’t an SE change because it was added in 1981. However, I strongly believe the pre-ANH version of Star Wars should be released as well because that’s the least they can do if they won’t release all of the movies in their unaltered forms, because Star Wars is the first movie in the saga, which makes it the most important.