I've received 2 good halfshafts from a B200E engined car, and have them stripped. Its interesting to see a pair of freshly used shafts, there was no corrosion in the joint atall, my previous ones have been sitting for a long time unprotected. Always cover the ends.
The uprated shafts are a fraction shorter (maybe <0.5mm), the main diameter is the same but there are 3 bumps of increased diameter along the length. Additionally the splines are longer and bigger diameter (24 splines compared with 22).
I can't see any difference in the outer race or balls.