The construction of the cheap regulator looks different but it looks plenty okay. As a matter of fact, it looks just like the ones that come in every rebuilt alternator for an MB that I've ever seen. I feel very good about it.
As far as the bearings go, it was not long ago that I put a new serpentine belt on this car. Every time I replace belts on anything, I always spin any accessory that is exposed to see that it turns smoothly before I put it back together. The alternator was fine. You did very good to get 140,000 miles out of a GM alternator. This is not, however, a GM alternator. I learned in this thread or another that this kind of mileage on these alternators is not uncommon. They MUST be made of Kryptonite.
Have a great day,