Huber Pontiac, Springfield, Illinois. It was on a corporate lease for 15 months before I bought it from Huber.
Interestingly, it was probably never at Huber Pontiac. Huber had it shipped directly from Lordstown to Portland, Maine. From Portland it went to the Minnesota company that leased it when their employee was terminated. (Yes, a 400HO red convertible Firebird for a company car.) From Minnesota it traveled directly to my home in the Chicago area after my dad spotted it and made a deal with Huber on my behalf.
It wore Minnesota plates in '68 and early '69. I still have those plates and use them on it at some shows.