The way I understand it [from verbal stories only] is that the Huey tailrotors were on the left side because of a US army requirement. Apparently the Army boffins thought that it was safer to have the T/R 'pushing' itself on to the output shaft in case of damage occurring to the retaining hardware when being shot at.
I came across a vague reference to this fact, saying that Bell modified the Huey T/Rs to the RH side but was then directed by the Army to return them back to the L/H side.