´68 BB vs SB K-Member difference?

SB A body K frames were modded into B/RB k frames "after" the basic K was pulled from the jig with the steering box, LCA, and idler arm locations welded in. From there they were modded into a B/RB K frame. I have seen a few of em, and quite honestly the first time I saw one, it looked to me like somebodies butchered to **** home brewed setup. After seeing 3 of em up for sale in 3 different parts of the country, and all of them looking to be modded exactly the same, this is the conclusion I came to.