the vacuum gauge was a rare factory option on the 67-72 trucks. that is why there is a blank opening in the dash cluster between the steering column and oil pressure gauge. there is an aftermarket retrofit kit available from several vendors. it requires the clear plastic lens w/ the word vacuum instead of a faux imgage, the inner bezel with the half moon punched out for the gauge to be visible and the back panel where the oil and vac sending units come out as well as other bits. the tach is taken into account 'cause anyone would want a tach also and it always came with the tach option also so the cutouts in the bezels and tach numbers on the clear lens are there. only problem is you don't get the a sending unit.
my home depot did not have the parts, but a local auto parts store should be able to supply you with brass-tite 43050 (1/8" npt female/ 1/8" npt female coupling) and brass-tite 43276 (1/8" npt male to 1/4" hose). i may have to replace the straight coupling with a 90 degree one on my 72 burb because part of the manual trans swing arm (3 on the tree) is right behind the vac gauge.
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