A boom assembly includes a first boom member and a second boom member slidable relative to the first member in a first direction. A stop member that at least partially defines a receptacle is attached to the first member. A closure member is attachable to the first member in a fixed position and movable away from the fixed position. A planar wearpad is insertable into the receptacle in the first direction when the closure member is moved away from the fixed position and the second member is positioned on the first member. The stop and closure members inhibit lateral movement of the wearpad in a direction parallel to the plane of the wearpad, and allow movement of the wearpad in a direction transverse to the plane, when the wearpad is positioned in the receptacle. The second member inhibits movement of the wearpad in the direction transverse to the plane.