There are so many things that can effect vacuum, like altitude, camshaft timing, exhaust systems, etc... that manufactures have not listed vacuum spec's for decades now.
Automotive engineers (and companies) drive me nuts.
It's another round of "It's a vacuum problem". "Okay, how do you know?" 'we just do'.
Determine vacuum problem: How, measure vacuum at different areas with things blocked off. What's it supposed to be? "Oh, we won't tell you. We just know".