Abstract: The invention provides an adjustable mounting assembly (5) for mounting a support stay (18) of a clamp arm (7) to a dipper arm (1) of a back actor. The mounting assembly comprises an elongated mounting member (9) defining a longitudinally extending central axis for mounting on the dipper arm with the central axis of the mounting member extending substantially parallel to the dipper arm and an anchor member (17) for anchoring the support stay to the mounting member. The anchor member is selectively engageable with the mounting member in at least two anchor locations spaced apart longitudinally along the central axis of the mounting member. The anchor locations position the clamp arm in an operative orientation with the clamp arm extending outwardly from the dipper arm for co-operating with a bucket mounted at the distal end of the dipper arm or in an inoperative orientation with the clamp arm and the support stay extending substantially parallel to the dipper arm.