I had the same question
A while back, I was considering plucking rear axle 1/2 shafts from a 116 at the local boneyard. I wound up decideing against the swap. However, I did compare the parts numbers on Fastlane (per another member's recommendation) and they were the same. I still wasn't 100% sure but it seemed like the simplest and most logical way of finding oput what fit. Hope this is of some help.