1984 BMW 318 Rear end howls.

I haven't driven this car much in the last 10 years. There have been some 'sticking spring' noises and feelings associated with clutch depressing and releasing. I assumed the howling noise at road speed was associated with a clutch problem. An experienced mechanic friend drove it yesterday and believes it to be a rear end problem. We're looking for free info on the specs and clearance settings, as well as what lube to use after repair. Working on it today, so fast response would be great. Not apposed to purchasing the repair manual info on line, but would prefer free.