Try California Pontiac Restoration (CPR) in California.
https://www.pontiacparts.net If a part isn't listed on their website, give them a phone call as it may not yet be added to their online inventory. I've bought a few things from them in the past that way.
Another possible source is Steve Barcak at Pontiac Heaven in Arizona. He's a member here but also runs his own website.
http://www.pontiacheaven.org