It is highly recommended that you install the manual hubs because the way these trucks are set up is fairly stupid. Instead of manual or auto-locking hubs, all we have is a cap with splines inside it, so it is a "permanently locked" hub. This means that it turns the CV shafts and wears out the CV joints, which will be accelerated more when you put a lift on your truck.
So, by putting the manual hub on and setting it to "FREE", your CV shafts do not spin with the wheel, thereby saving you wear and tear, and also netting you slightly better fuel economy.