69 340 k member? Help

I've typically seen that on 68 and 69 A body K members when they were 340 (68 - Formula S / GTS) cars. I haven't inspected enough BB 383 cars to know if it was a SB K member only thing. All the 67-69 A Body K members I've see had the sway bar holes drilled into them. Supposedly, the welded washer was to let the guys down the line know it was a Hi-Po car??? Maybe those are the cars (outside of the 'verts that got the torque boxes? IDK. I know there were older discussions along these lines... is that what you were looking for?