I'm guessing this has already been covered many times but not able to find what I want so i am asking.

I am installing a boost guage on my 93 300D, 2.5T. I would also like to put in a separate vacuum guage to monitor my vacuum pump workings (had that fail last year).

• Anyone got a suggestion on what scale guage I should get (no idea how much vacuum I should get at idle and cruise for instance). I don't want to max out a guage or have one that has too big of a scale. I assume maybe a 30 mm Hg guage full scale or so but really haven't got a clue about this.

Just to be clear, I'll be installing 2 guages, one for manifold boost pressure only and one for measuring the vacuum line pressure (vacuum). Kind of hard to find guages too locally. All they have are the bidirectional vac/boost guages and obviously on the diesel that isn't what I need as those systems are totally unrelated unlike the gasser situation with a turbo.

2nd question.

• Anyone got advice on mounting guages in the ashtray area. Can I pull the whole flipper door on the tray and disconnect the lighter or how to folks do this. On my W124, there isn't much room other than the ashtray that I can think of. (anyone ever mount on the left side of the dash above the vent or on the door pillar and if so, got any pics?)