Do you mean where was Clinton Valley Center? Or do you mean where was the new Pontiac Hospital. I don't know what the new Pontiac Hospital is. never heard anyplace called that. There was no new Pontiac Mental Hospital that I was ever aware of if that is what you mean by new Pontiac Hospital.
valley center was a huge and beautiful place (when new). It took up a very large area from Elizabeth Lake Rd (east of telegraph rd) to telegraph rd. Entrance was on Elizabeth Lake Rd. I remember it as a kid.
There is a website on the place. search "Pontiac State Hospital" or "Clinton Valley Center".