ok ever since i replaced the first 2 joints, ive been going through them like butter, probably 5-7, all on the rear drive shaft, with a totally stock truck, and not really driving too hard. they look like they're burning up, are you supposed to pack them with grease before install? cuz i thought that vaseline lookin stuff was grease, so i didnt bother, so am i retarded? or can my drive shaft actually be bent? any help appreciated..