A tool for guiding a drill from both sides of a post having a top and at least one circumscribing side so that a single longitudinal axial bore is formed, the tool comprising: a first part adapted to clamp over the top of the post and position first and second guide plates on opposing sides of the post, the first and second guide plates having openings formed therein; and a second part adapted to position two opposing drill bushings in the openings in the first and second guide plates.