Replacing the boots is pretty easy. Make sure that you follow the directions. To find out if you need to replace the joints remove the grease from the end that you are replacing, get it cleaned up good so you can see the bearings. Look to make sure all the bearings are still there. See if there is any heat damage to the bearings, This is the bluing of the metal, see if it has damaged the seal that holds the bearings in. If not then put the boot back on then fill with grease and put back together. good luck.