It's a geofranger for a multifarb 9/8" compound wye. Very common for retaining compound wyes in a negative gravity situation, otherwise you will lose surface traction with standard class C macadam, and the energy consumption to overcome it otherwise would be prohibitive...
(How's that for a pile of "stuff"?

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It looks like someone's homemade flatbed trailer wrench, either to snug up the ratchets (see BroncoSquid's picture above) or to move the 5th wheel back or forward to balance weight. Since it was found near a road train, that makes a lot of sense - someone probably set it on one of the trailers or on the frame rail of the tractor and it fell off...