I've read the story a few times. It is quite different from the movie. I can't remember the exact details, but Jack had a thick butt with buck teeth and a concave chest and Ennis was thin and wiry. Or maybe Ennis had the concave chest. Later on, Ennis had a growth on his eyelid. Neither one was very appealing. In fact, if you picked a couple of cowboys at random, they would certainly be way more attractive. Annie Proulx always revels in life's less savory aspects and often uses some literary license. She likes to inject a lot of ugliness and stupidity into the characters in her stories. I don't know if she is making a statement about Wyoming or life's underlying sordidness. Anyway, I have often wondered why the movie features Hollywood's biggest studs to play a couple of mostly unattractive characters.
This is my first post.