There is NO stock vacuum line run past the firewall... none.
I said stupid shit because YOU posted and asked where the vac line was... I told you, then you argue that it has to be behind the dash because that's where the hissing is... THEN you admit to having put a vacuum line behind the dash yourself... And now you try and twist everything I said about the noise possibly coming from the stock gauge and you seemingly ignore the part about diagnosing your mechanical gauge (the diaphragm is in YOUR gauge, if it holds pressure, you test the hose next)?????
No worries though. I haven't the patience for this right now, so I'll step aside. Good luck with the problem.
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