AUX Power

One of the easiest places to get auxiliary power in a later model Astro/Safari van is the upfitter power studs. Generally Stud A is switched with the ignition, as it's tied to the Upfitter Ignition Relay. Stud B has power all of the time with both studs are protected by their own 30amp fuse.

This will vary by year so check your wiring diagrams or check them yourself using a meter. As always when you are adding circuits, never forget to add circuit protection like a Fuse/CB/FusibleLink