There were two occasions when I put the instrument panel back in and forget to attach this vacuum tubing to the gauge. It's pretty much impossible to connect from underneath too.
So... I got smart and created some markings. For this vacuum tube, I used some white heat shrink tubing that came from Harbor Freight over the black rubber tubing to make it more noticeable. Then I cut it about 5 inches behind the gauge and put a inline connector there.
My round harness connector has one inch long piece of blue zip tie super glued to its outside marking where the locating key in its center is (idea taken from the factories V notch on a steering box coupling), and its wrapped in white electrical tape. I can see and feel the little piece of zip tie so I don't need to see the factories key in the center to know where up/orientation is.
I didn't come up with a good orientation helper for the inline connector on the smaller board. Since that time another member here showed a slick mod for it. The 3 wires soldered onto the board, male and female harness connectors inline away from the board.
