G'day Usedtobe, You may have better luck if giving more detailed description, part numbers or photo's even - There have been many HR Hitch combinations. All have been designed for specific weight/load. some have cantilevered chain attachment other use lifted bar into slide, there are even different size towball.
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Possum; AKA:- Ali El-Aziz Mohamed Gundawiathan
Sent from my imperial66 typewriter using carrier pigeon, message sticks and smoke signals.