This class was built around the standard 42'-0" post-war underframe. It initially came into being as the result of rebuilding surplus TA class cattle trucks into flat tops for container traffic. The class was then multiplied before conversion to other groups. The most common conversion involved the fitting of extension brackets at each end and reclassification to QCE. Building and disposal of the class is summarised as follows:

1957	23606, 23609, 23621, 23626, 23637, 23662, 23665, 23679, 23687, 23688 ex TA
1959	23586-23600 built
1960	23576-23584 built
1962	23620, 23638, 23640, 23644, 23645, 23648, 23649, 23650, 23657, 23658, 23667, 23673, 23675, 23677, 23678, 23685, 23686 ex TA 23590, 23591, 23600, 23721, 23658, 23667, 23687 to QCE
1963	23578, 23579, 23581, 23587, 23588, 23589, 23592, 23593, 23594, 23595, 23596, 23597, 23599, 23606, 23609, 23628, 23644, 23649, 23657, 23673, 23679, 23688 to QCE 23581, 23658, 23687 ex QCE 23665 to QCD
1964	23586, 23650, 23685, 23687 to QCE 23579 ex QCE
1965	23598, 23662, 23678, 23686 to QCE
1967	23677, 23640 to QCE
1969	23648 to QCE
1970	23585 ex QCA
1981	23582 to QCG
1982	23580 to QCG
1993	23585, 23645 written off
1996	23576, 23577, 23578, 23579, 23581, 23583, 23584, 23658, 23675 written off

The WAGR outline diagram is shown below.

There were also two similar MRWA NC class wagons which were added to this class in 1964 (40751, 40752). They were both written off in 1992.