(2014-2018) GM Truck 1500 2500 Billet Vacuum Supply Port Fitting14 18 GM Truck Billet Vacuum Fitting This fitting gives you a clean and simple solution to get a vacuum boost reference from your factory intake manifold. It bolts into place where your factory evap line goes. Then you can route a line to your BILLET VACUUM SUPPLY BLOCK, or directly to your wastegates, blow off valve, boost controller, ect. The 8AN 90* fitting can be used to mount a vacuum block directly to the intake manifold.