Where does the vacuum line go from fuel pressure regulator on a 2000 Chevy 4.3 vortex?

On a 2000 Chevy 4.3L Vortec engine, the vacuum line from the fuel pressure regulator goes to a ported vacuum source on the intake manifold. It's not connected to manifold absolute pressure (MAP) sensor vacuum or a vacuum line that goes to the brake booster or other accessories. Look for a vacuum port on the intake manifold itself – often a smaller nipple – that is under vacuum only when the engine is running.