CUTLASS heater control vacuum hoses

[supreme 88]

I have a 1988 cutlass supreme classic that I need to find the heater control vacuum hose connections, the gray hose goes to water valve there is a violet hose and black hose that I don't know how they connect. I am wondering if there is a diagram or picture of where they connect

 

[ELCAM]

Off the top of my head the purple line goes to the vacuum tank under the hood it is the vacuum source. Have to look up where the black one goes.

Edit:
Black is from the manifold to the tank, tank to control is purple,