Abstract: The stabilizer extensions are brackets with rollers employed for stabilizing a large boring head when drilling a bore hole in the earth. A hub is provided for attachment to the head. The hub has a plurality of mounting plates located around its axis and radially outward therefrom. Each of the brackets has a bracket mounting plate at one end and a roller mounting plate at the other end. A roller is attached to each of the roller mounting plates for engaging the earth for stabilizing the head. The axis of each of the rollers defines a scalene triangle with two side edges of the bracket mounting plate of its extension bracket. The bracket mounting plate of each of the extension brackets is adapted to be attached to any of the hub mounting plates in a first position or turned 180.degree.