So I have an opportunity to buy an empty cab but I'm a bit confused on it's age. There is no grill on it and a 9 inch logo (I think it's 9 inches, maybe it's 11). It has legit metal handles, and a birch back panel, but it has corners. The corners are throwing me off. Did they do corners in 70 or 71? I didn't think they did that till 72.