I've never had problems uneven rear tire wear in my W 110 caused by improper camber on the rear wheels. That car uses the same type of rear-end as your W 108 with a compensating spring rather than the hydropneumatic unit. I will say, though, that I don't do a lot of driving with the car 'fully loaded' with heavy cargo in the back. It's good, by the way, that you were able to get to that pinion seal quickly. Those are often neglected and the rear-ends run low on fluid, resulting in damage that causes them to 'whine'.