Rear Differential The rear differential is located centrally in the rear subframe. The front of the differential is attached to the subframe via rubber bushes and bolts. The rear of the differential is mounted to the subframe via a single, offset rubber bush and a bolt. The casing comprises two parts. The pinion housing is made from cast iron and provides locations for all the internal components. The pinion housing is sealed at the rear by an aluminium casting which is secured to the pinion housing with eight bolts and spring washers. A gasket between the two casings seals the unit. The rear cover has cast fins which assist heat dissipation. A breather tube is fitted to the rear cover. This allows a plastic tube to befitted and routed to a high point under the vehicle body, preventing the ingress of water when the vehicle is wading. The rear cover contains an oil level plug which allows for oil filling and level checking, with the differential installed in the vehicle. The level plug allows the unit to be filled with oil until it leaks from the filler hole, ensuring the correct quantity of oil is added. The differential unit contains approximately 1.2 litres of oil from a dry fill. If oil is being replaced, a smaller quantity of oil will be required due to residual oil retained in the pinion housing. The differential is a conventional design using a hypoid gear layout, similar to the front differential. The rear differential is available in two ratios. V engine vehicles use a differential with a final drive ratio of 3.73:1 and Td6 engine vehicles use a final drive ratio of 4.10:1. The ratio is changed by changing the amount of teeth between the crown wheel drive gear and pinion gear. Therefore fora ratio of 4.10:1, the crown wheel drive gear will have 4.10 times more teeth than the pinion gear. This equates to the crown wheel drive gear having 41 teeth and the pinion gear having 10 teeth.