Both will bolt right up.
Driveshaft mods will probably be needed as well as shift linkage mods.
But this is a great swap and easier than most think.
The 231 is cheaper, but I would go for the 242 if I were you, unless it never snows where you are. Not having the ability of full-time 4wd is lame IMHO.
6", 35's, Detroit/OX, L10, 4.56, Warn 9500