The (removable, gold-colored) stud end of the 042 (left side of the picture at B&H) should fit inside the extension arm. The fixed (grey) hex stud end (right side of the B&H pic) should fit in the SuperClamp, but I don't know if it will fit in the extension arm (might not be deep enough before the hex gets in the way).
Also, if you don't want to grind down the fixed stud's hex edges to provide for free rotation in the SuperClamp slot, you might consider the
203 Extension Arm for Mini Clamp. FWIW, I use it with my SuperClamp. Allows free rotation of the arm when I insert the fixed-stud end into the SuperClamp and has the same flexibility / removable stud on the other end. The arm is slightly shorter, though, 4.72" v. the 042's 6".