If I remember correctly... the two "foot-blocks" are added to the sides of the vang "key block" through the "vang tang" pin holes on the key block. That is, the pin at the bottom of the vang key block is removed. It is replaced by a longer bolt and lock-nut of appropriate diameter and length. This bolt goes through mounting holes of the two foot blocks positioned to either side of the vang key block. Best. Shevy.