Assuming you need new U-joints on the shaft I will try to explain... First remove the bearing retaining u bolts from front differential and the tranny. Be careful while separating the shaft from parts( you may have to use a pry bar) that the bearings do not fall out of the cups. There are snap rings on one side of the U joint, remove those with a pair of needle nose pliers and then prop the shaft on a 2x4 or something and pound out the old ujoint with a ball peen hammer and a socket so you do not bend the shaft where the ujoint is in. Once you have it loose wiggle it out and reinstall the new ujoint but do NOT pound it in with the hammer you'll end up damaging the new bearings, repeat with other side if needed. Hope this makes sense and helps you out.