The driveshaft is a long tube extending from the transmission to the rear end housing and supplied at the two ends is supplied with what are known as universal joints that allow the shaft to transfer power to the rear wheels despite the fact that the wheels may be at right angles to each other. In front, it comes with a splined yoke which engages with the extension housing of the transmission such that it moves from side to side while in use. An oil seal avoids the loss of fluids and the intrusion of undesirable substances; if there is seepage, the oil seal will have to be changed. The driveshaft assembly only needs little servicing because the universal joints are pre-lubricated and can only be replaced when one has problems which require the withdrawal of the driveshaft from the car. The alignment of the driveshaft is very important, therefore it should be very clean, and checked for signs of damage, also the small weights that are used to balance the shaft should not be lost. Depending on whether the problem involves noise or deliberate vibration while driving, a road test can be carried out to validate if 'the' driveshaft is the cause. This includes recording the magnitude and frequency of the complaint as well as the network speed at which the problem is particularly noticeable and varies the vehicle in a range of gear. If the noise or vibration increases with the increase of engine speed then the driveshaft does not seem to be the problem. On the other hand if the problem reduces or disappears a physical examination of the driveshaft to determine the presence of any damage, balance affecting material, missing weights and indications of damaged universal joints should be carried out besides checking for balanced tires. To inspect worn universal joints, one may accelerate slowly in High gear, or coast and then accelerate and listen for clunks or knocks, it is also possible to coast in Neutral at low speed, to hear any strange noise. Further, if the vehicle is raised and the driveshaft is manually turned while looking at the universal joints for a lot of play, then, this indicates that they may have worn out.