its head 49 visible in dotted outline in fig2 is placed directly against the inner surface of the siderail 28 of panel 24 second wedge bolt 48 is then inserted in a slot 50 in the shank of wedge bolt 46 with its head 52 and point 54 disposed firmly against the inner surface of siderail 28 of panel 22 thus wedge bolt 46 is secured in said pair of slots 30 firmly attaching said panels 22 and 24 to one another note that clearance for the point of second wedge bolt 48 is provided by slot 42 when used the first end 14 of attachment 10 is inserted into void 36 and hole 18 is aligned with the pair of slots 30 then a wedge bolt 46 is inserted through the slots 30 and hole 18 and secured by the other wedge bolt 48 in the usual fashion hole 20 which extends beyond siderail 28 is then available to receive the hook of a safety belt not shown as seen in fig2 the width of attachment 10 along its short axis preferably is significantly smaller than the longest dimension of void 36 thus the attachment is free to rotate to an extent about wedge bolt 46 in reaction to an upward or downward force applied at the.