A common problem for the MGB with Salisbury (tube type) rear axle is too much freeplay (backlash) at the input shaft caused by worn thrust washers in the differential. This results in a loud CLUNK on start, stop, backing up, or even just a change of accelleration while driving. Today we got to fix one, and it’s not that big a job. Lift the car, set the body on jack stands and lower the rear axle to the limits of the rebound straps. Remove the rear wheels, drain the differential oil, and remove the back cover from the differential. Remove one rear brake drum and pull one halfshaft out a bit. Tap out a spring pin, pull out the pinion pin, and all of the differential gears practically fall out in your hands. Replace any worn (or missing) thrust washers, and reassembly is the reverse of disassembly. Install fresh gear lube when finished. The job was done in under two hours, so it was natter ‘n’ noggin time.