Now, some of the wampa stuff was filmed; did that survive Kasdan’s rewrite?
I think there were later drafts between Leigh Brackett’s first one and the final script. These were probably much closer to the final version, but still included Wampas invading the base. That’s why those deleted scenes with the Wampas exist. But the Wampa attack on the base in Brackett’s original draft is so dramatically different than even those deleted scenes. In Brackett’s version, the Wampas seem ridiculously powerful and dangerous - they kill dozens of people instantly. Some of these scenes have horror-movie vibes. There’s one scene where you hear over a communicator device as a room full of people are massacred by a Wampa. They’re also very hard to kill. Han shoots at one of them and somehow the Wampa is fast enough to dodge it.
I’m also not sure how Brackett envisioned these creatures, but the script implies they’re more like some kind of ice monster than a giant Yeti. Luke kills one of them with his lightsaber, but the script says that when Luke slashes at it with his lightsaber, the monster turns into a cloud of vapor or something. I have no idea what Brackett is going for here… Are they made of ice? Are they supposed to be supernatural? Did Brackett think that anything that dies from a lightsaber just disappears (like Kenobi in Episode IV)? I’m really not sure what’s going on there.
Regardless, the version of the script that was the source for those deleted Wampa scenes must have been a later revision, written probably by Kasdan between Brackett’s first draft and the final version. It’s funny that ultimately after all these revisions, the final script removes the Wampa stuff entirely (except for the one that attacks Luke). I’m glad they removed it, it’s just weird how significant the Wampa stuff was in the earlier versions.