Hi Randy -
I believe your cabinet is a model 215S, which was the cabinet supplied with the solid-state Concert Bass amp. I have one and really, really like it. It has the same exterior dimensions as a 200S cabinet, but is front loading with, as you describe, the 15" drivers vertically aligned to the left of center, and the two vertical horn ports on the right. Mine has a identification plate on the upper left corner of the cabinet back. Rocketboy