"CUT, PRINT - AND THAT'S A WRAP", by Paul Helmick.
Written in 2001, Howard Hawks' reliable assistant director and 2nd unit director Helmick tells the tales of his Hollywood years. He was around when they made some of the Hawks classics, as well as the films with Wayne: Rio Bravo (it was him who suggested to cast Dean Martin to Hawks), El Dorado, Rio Lobo. Of special interest I found his descriptions of working in Africa on Hatari. This must have been the techniqually most difficult film to make up to that point! Helmick would go out and shoot animal action (with, yes, the doubles) then call Hawks who would come in the next day and shoot scenes they just made up so they would fit to the things Helmick got in the cane. For the spectacular entrance scene with the Rhino, they just happend to find one that was mean enough to attack Bruce Cabot's double and they got it on film - the double acted as if being horned. So they wrote the whole entrance around it - writing Bruce Cabot out of the film for a large part of it (for all of us who forever wondered why his "Indian" character was in the film anyway). No wonder it took Hawks more than a year to assemble the cut (other Wayne releases before Hatari were actually shot AFTER it, he moved to Africa right after Alamo, and, according to Helmick, was glad to because he wanted to get away from it).
Helmick also says that him and Wayne never got really friendly, he thinks that Wayne held one incident against him, when Wayne and Hawks were discussing what Ricky Nelson should say when asked by Chance: Pretty young for riding guard, don't ya, and it was Helmick who just came up with the cool line: Just how old you gotta be? Obviously, Hawks didn't tell Wayne that Nelson's response would be just that (he often didn't tell his actors to get a natural response) and Wayne barked: "Since when does the 2nd assistant get to write the dialogue?!"