Actually they are not that bad, depending upon if they come out with the axle or stay in the housing. My Nissan the bearings were press fit to the axle and came off with it so I took just the axle too a shop that had the equipment to press off and on the bearings. If the bearings stay in the housing then all you have to get is a bearing puller to remove the old ones and then a something to install the new bearings. To check to see if it is bearings you can jack up the rear of your truck, making sure that you block the front end, then spin the tires with the e-brake off. You should feel and hear anything that is wrong.
Something else check the brakes over first before you go all out on the bearings. If a master cylinder is sticking then it could also make noises like what you describe at times.