So it's fairly well known to nerds in the know that Lucas' friends and colleagues Gloria Katz and Willard Huyck did an uncredited dialogue polish on the final draft of Star Wars prior to the film going into production.

I'm not familiar with the many drafts of SW, shooting scripts and what has been made available for the public to read.

Can anyone here give me a bit of detail in regards to this? What was the draft they contributed to (obviously the final one)? Are there versions available that can be read pre and post Katz and Huyck polish?

I do know that SW evolved a lot from drafts to screen and I'm curious as to what the difference is between Lucas' final draft, the script that was given to crew and actors in pre-production, to what was shot on the day. If it's very little or simply that material has not been made available I won't bother looking any further.