You found an 86-87 SD? Midbadged, perhaps? The 86-87 SDL didn't come with an economy gauge. Maybe someone retired my gold 87 SDL which had the same mod

I had problems with an 88 or 89 300SE 4-gauge panel in my 87 SDL so I made sure to get an 87 300E 4-gauge panel for this mod.

In my case it's also an economy gauge. I figure I use less fuel in the black than in the red.

It's not a great boost gauge because it's highly damped. It's between 1 and 2 seconds slower than a VDO 0-30 psi boost gauge I used as a reference. There's only about a 7 psi spread between posts so you can't have it tell you how soon boost builds and how high it'll go. I just like to see it swing when I go up and down the hills on I-280 with the cruise control

And nothing but premium unleaded Diesel goes into the tank. So there

Sixto
87 300D