Yes, the two go together. Hoever, you don't need a new rod, unless yous is damaged. You can remove the old brearing bracket and drive bushings out with a small hammer. The ball joint piece, with the threaded rod, can be driven out but there will be a lot of rust from the metal retainer. The bracket is aluminum.
You need the bearing bracket bushing,
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1B10RC08K1UO0QIGIF&year=1989&make=MB&model=300-SE-001&category=L&part=Bearing+Bracket+Bushing
Guide rod mount kit:
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1B10RC08K1UO0QIGIF&year=1989&make=MB&model=300-SE-001&category=L&part=Guide+Rod+Mount+Kit
When you look at the service manual, you will see the guide rod mount being driven in to the bracket with a small plastic hammer on the edge. I used a large, ie 25 mm wrench, on it's side and on the outer metal portion. Don't use a press on the center of the back portion. I did this and had to replace the mount after a year. It was damaged internally.
I replaced all the rubber bushings in the front suspension, as well as the ball joints. I bought a sprint compressor and did one side at a time.