I found information on servicing the ALDA, by cleaning the banjo bolt on the rear of the exaust manifold, that leads to the switchover valve. I first checked this bolt on my 80 300SD since I'm parting it out, to mkae sure I could remove it without causing harm. It was surprisingly clean. So whats confusing me is that when I checked this bolt on my 79 300SD it was half the length as the one I pulled out of the 80, which looked just like all the photos I've seen. Can anyone tell me if this should, or should not be so? Any info on this subject is helpful. Thanks!