I am in the process of picking up a 1980 450 SEL and I know that the previous owner had problems with the 'relay.' I use this term loosely because I do not fully understand if the MB part dubbed a 'relay' is in fact a mechanical relay or a bit more. So my first question is, what is this device? I have not been able to disassemble the 'relay' to view its contents. I will be driving up north of Pittsburgh on Saturday to further mechanically insect the vehicle. My visual inspections two weeks ago were very pleasant. The vehicle itself is in decent condition as far as the frame is concerned, showing a bit of flaking of the clearcoat around the hood, but solid otherwise. Excellent interior, etc. So, when I get up there, I'm going to check it out further, starting it and soforth. The other question I've been going over is whether it would benefit me to pick up the 'relay' regardless of whether the old one works or not... Is this a part that would make sense to have in my inventory for a 'just in case' scenario? I've seen several posts about the relay and wonder if this is a part that has a pretty static lifetime.

Your comments are appreciated and I will post pictures once it is ready for public viewing.

And of course I would be ordering the part through the part shop of this site.