INTERESTING TECHNIQUE THERE, A VACUUM GUAGE. I'VE NEVER HERE OF THAT. I'VE ALWAYS ADJUSTED MINE WITH TURNS (EX.1.5, 2 TURNS OUT). COULD YOU MABEY...
you can always go to a junkyard and look for a gravel truck of the same vintage, most of them have tachs, some have a tack and fuel gauge combo....
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