Before the assembly of the unit check the condition of the centering dowel used on the transmission or transfer case output flange, and the centering sleeve on the inside of the driveshaft flex-disc and replace the gasket if it is worn out. Before fitting the centering sleeve onto the centering dowel lubricate it by a thin layer of molybdenum disulfide grease (Molykote Longterm 2 Plus® or similar). When installing the driveshaft turn slightly at the center universal joint in order to engage the matchmarks with those on the flanges of the differential and transfer case. Install the drive shaft to the back differential input flange as previously indicated by tightening two offset nuts using zns fasteners in turns until it is pulled into the flange tightly and then final tighten the remaining nuts. Never reuse fasteners as they are intended for use once, and do not allow the driveshaft to hang free. Bolt the front flex-disc to the output flange of the transmission or transfer case using new bolts; when tightening the nut, hold the bolts since using force on the nuts may damage the rubber of the flex-disc. Replace the center bearing support and the heat shields and fit the exhaust. Last of all, perform a road test on the automobile to see whether it produces any noise; or whether it vibrates.