Darabont's draft is so much like what became Indiana Jones and the Kingdom of the Crystal Skull that until I know why, it's going to be an eternal question in my mind as to why he never received a writing credit for the final product. It's the same basic story: Jones gets involved with a quest for a seemingly-mystical crystal skull and the adventure winds up in Peru. The space aliens angle is still here. So is the rocket sled, the mushroom cloud, and the refrigerator (but those all date back to Jeb Stuart's Indiana Jones and the Saucer Men from Mars script in 1995 anyway). Mutt is not in Darabont's script, but Marion returns here too... and I have to say that Darabont's script might have captured the spirit of her character more than what we saw in Kingdom of the Crystal Skull. There are many references to the previous entries in the series: some pronounced and others very sly (especially one thing that hearkens back to the first time we see Indy and Belloq meet in Raiders of the Lost Ark). Sallah and Henry Jones Sr. have some fun cameos in Darabont's script, too. Oxley also figures in Darabont's story and doesn't feel as tacked-on as he did in the actual movie.
Now please don't get me wrong here: I loved and still love Indiana Jones and the Kingdom of the Crystal Skull. There are numerous elements in Darabont's draft that I wish had made it over to the finished work, however. I liked the new character Yuri and the dialogue he shares with Indy and I could easily picture Ray Winstone in the role, too. The aliens are a much bigger threat and per Darabont's pen feel very... well, "alien", in a Lovecraftian way. And Indy himself comes across as more happy-go-lucky and whimsical: a sign of the growth that he has undergone as a character after so many adventures.
Anyhoo, it's out there, if you want to read it for yourself. Good luck! :-)