A few weeks ago Cloninger Ford in Hickory, NC had quite a few. I wouldn't pay $38 for them and saved a few bucks at LMR.com. But sadly LMR is out of stock.
https://www.cloningerfordofhickory.com/contactus.aspx
Bought one from Late Model Restoration a couple weeks ago. No stock now.
Amsoil?
https://www.amsoil.com/lookup/auto-and-light-truck/2017/ford/mustang/5-2l-8-cyl-engine-code-z-99z-z/?volume=us-volume