are formed at equally spaced positions along the length of mounting plate 118 and aligned therewith are six openings 127 formed through the opposite mounting plate 120 shank 94 is flared outwardly at its lower end 130 and a pair of transverse openings 132 are formed through this end the transverse openings are sized commensurate with the mounting plate openings the shank openings are also spaced apart in a longitudinal direction commensurate with the longitudinal spacing between the mounting plate openings with the shank lower end inserted between the mounting plates as illustrated in fig8 the two shank openings can be positioned in alignment with a corresponding pair of openings in the mounting plates with this arrangement there are five possible positions at the which the shank can be mounted longitudinally of the counterweight body fig7 illustrates the mounting of the shank at a central position in which the shank holes are in alignment with the innermost pairs of mounting plate openings 126c and 126d steel pins or bolts 136 and 138 are inserted through the aligned openings as illustrated in fig8 and secured by lock pins 140 with the bolts 136 and 138 removed the mounting location of the shank on the counterweight body can be changed by moving the shank openings into alignment with a selected pair of mounting.