In our shop we charge $100 to swap a rear axle in if it is a bolt in. Front axle we charge a little more due to steering linkage. Setting up a set of gears is right around $300 per axle. It's really easy to do. Take the weight off the truck and unbolt the brake line, u bolts, shocks and drive shaft. Roll the old axle out and roll the new one in and bolt it all in. On a lift I do it in way under a hour.