I had the swing arm powder coated, so I removed the drive shaft before taking it to the powder coater.
The 1983 R80ST swing arm is designed for a monoshock rear suspension, but the driveshaft is the same as the one used in the dual shock 1983 R100RS. I previously removed and installed the driveshaft in a 1983 R100RS and documented the work. So I will not repeat the procedure here, but link to it as appropriate.
1983 R100RS Dual Shock Swing Arm Design
1983 R80ST Powder Coated Monoshock Swing Arm Design
This is a link to the documentation and a YouTube video showing how I remove and install the drive shaft.
VIDEO: 1983 BMW R80ST Remove & Install Driveshaft