Just picked it up! It's actually a prototype model made before full production of the Model T. It was quite possibly made when Sunn was still based in Portland. It's a very special and awesome sounding amplifier. I have many more photos left to take of it when its retubed next week.
I'm selling the 1971 Ampeg V4, but for a time it sure is great having both. (And yes I know the picture is ghastly too big, i'll resize it later)