Novelizations of original screenplays don't get much respect in the literary world, do they? I'm trying to think of highly-regarded novelizations, and the only ones I can think of that get any regard at all are in the science fiction field. As far as I can tell, Leigh Brackett's novelization of the screenplay for Rio Bravo that she co-wrote with Jules Furthman, which was published in the year of the movie's release in 1959, has never been reprinted. I'm not saying it necessarily deserves to be reprinted, but it does seem like a strong enough work in its own right, with plenty of Brackett's trademark terse story-telling panache.
I believe novelizations are generally based on the screenplay and not on the final cut of the movie, because the idea is to get the book out at the same time the movie is released. I'm not so intimately familiar with the Howard Hawks film that I could spot all the differences, but I did watch the movie again a few days after I read the book and did spot a few differences. For instance, the book ends with Dude and Stumpy gleefully discussing Chance's prospects with Feathers, where in the film there's another scene between Chance and Feathers. The beginning is different too, with two chapters from the point of view of Pat Wheeler as his wagon train arrives in town and is momentarily halted by Burdette's men. (This is referred to in passing by Wheeler in the film.) The book includes a scene where Colorado shoots at some of Burdette's men as they ride by on horseback that isn't in the film, and I actually just spotted the scene in the book where Chance puts Feathers to bed that's not in the film. Instead of the scene in which Dude and Colorado sing songs (which I don't think I'd ever seen before, probably because it's edited out of most TV showings of the film as dead space), the book just briefly mentions Colorado singing to himself and Chance overhearing it.
In general, and as you'd expect, the book has more description of what the characters are feeling and thinking and what happened to them in the past, although there still isn't a lot of backstory. I think the book actually works somewhat better than the movie in terms of the characterization, because: a) Ricky Nelson and Angie Dickinson aren't all that great at putting their characters across, and b) John Wayne is always John Wayne. Not that John T. Chance is much more than a generic heroic sheriff in the book, but he doesn't come across as "the John Wayne character" the way John Wayne always does. In fact, another thing that has always mildly bugged me about the film is that Wayne seemed a little too old for the part, especially the romantic parts of it (which are also painfully generic).
The book includes one piece of dialogue that actually kind of shocked me and seems completely uncharacteristic of Brackett. In the conversation between Wheeler and Chance in the hotel saloon, where Chance tells Wheeler to stop trying to find help for him and Wheeler sneers at the alcoholic Dude, Chance explains to him what drove Dude to drink: "A green-eyed, yellow-haired, two-titted female." As I say, it seems unlikely to me that Brackett wrote this crude line, although I can't say for sure that she didn't. It's also at odds with the film's fairly shy, boyish attitude toward women, and there's absolutely no way it would have made it into a mainstream Hollywood movie of that era. Was it just thrown in to give the book readers something a little spicier to chew on? Very strange. Another slightly racier aspect of the book is that the fancy red see-through underwear that Carlos buys for his wife, Consuela, are later seen being worn by Consuela herself.
Well, I guess I'll say that the book was better than I thought it would be, and leave it at that. I think it would be interesting to scholars of the movie, but its rarity probably makes it hard for them to get their hands on it. Not that I've read a lot of scholarship on Rio Bravo, so what do I know. It's also definitely of interest to Leigh Brackett fans. It's not as good as her original Western,
Follow the Free Wind, but it's not as far off as you might assume. A really solid piece of writing based on a superior if old-fashioned movie. (Watching the film again, perhaps the first time I've actually watched it all the way through, reminded me that Hawks borrowed some elements from Sternberg's 1927 gangster film, Underworld, for reasons that are still unclear to me. But that's a subject for another day.)