it's not a commom problem, the driveshalf couplings and boots need to be inspected often and grease aleast once a year. A injection needle with outboard grease will work fine. The o-rings tend to dry out on the driveshaft boots with age allowing mud and water to get inside the boots washing the grease out of the them. With no grease in the couplings, medal on medal is not going to last very long.