I have a 2001 BMW 740iL. I already changed the tail light on it and wanted to put in new side markers as well. I was going to put up instructions with photos on how to do this but it literally took 60 seconds to finish it so I didn’t have time to take photos but this one.
Here is how to do it:
1. Pull out old side marker with the help of a flat head screw driver
2. Pull out the bulb and place it in the new marker
3. Push the new side marker in. You’ll hear/feel an obvious click.
I picked up my side marker from eBay. It cost 25$.