Seems that all are very different for some reason, same as for fuel guages where empty means some will stop and others still have 100Kms left in them.
Perhaps the guages can be remapped similar to the fuel system, as everything runs off the computer in some way.
The older model holdens fuel sender were simply adjusted by bending the float connected to the tank's sender unit while watching the guage as the float was moved through the arc of it's different positions outside of the tank and comparing the guage to the senders relative position.
Different temp senders made at different times may give different readings.
Perhaps best to say they are commodores and leave it there if they work in some way.
In very heavy trafffic and 40+ outside my temp guage has never hit 1/4, it obviously works but is set differently to others for whatever reason.