Hey all, was in the junkyard the other day just browsing

and saw a few clusters on w124's that had the economy gauge that my 91 w124 does not have. When I had my 86 it had it, and I rather enjoyed it, could see how my lead foot was doing and it was something to fill that empty space. I don't remember the setup at the junkyard and I vaguely remember the set up on my 86. From what I gather, the vacuum lines should all be there for it? There should be three, right? Is it as simple as plug and play?