Previously, I replaced the swing arm bearings and you can read about how I did that here:
Now I install the swing arm in the frame and then install the rear drive on the end of the drive shaft side of the swing arm. I show how I align the swing arm in the frame to reduce stress on the drive shaft when I install it. The rear drive mounts easily to the flange on the right side of the swing arm with four 12-sided nuts.
Here is a link to the procedure:
And here is a video summarizing how I did the work.
VIDEO: 1983 BMW R100RS Install Swing Arm & Rear Drive
I had the swing arm powder coated and cleaned up and I refinished the rear drive that had been sprayed black with rattle can paint.
Here is the final product.