This class was created by the conversion of both steel and wooden bodied RB class wagons in 1970. Further conversions occurred in 1971 and these also included two RBT class wagons. However in 1971 four class QRC wagons were converted to class QRN. Seventeen more followed in 1972 although six wagons were also reconverted to QRC in the same year. In 1975 a total of five QRC class wagons were converted to allow them to carry end-tipping nitrate containers as class QRD.

1970	1025, 4133, 4572, 4904, 5719, 6360, 6457, 6483, 6506, 6516, 6544, 6813, 6875, 6910, 6941, 6985, 7055, 7072, 7133, 7136, 7163, 7232, 7237, 7239 ex RB(wooden) 759, 782, 791, 804, 947, 2560, 11201, 11247, 11261, 11265, 11289 ex RB(steel)
1971	3836, 4232, 4274, 4311, 4434, 4498, 4627, 5101, 5162, 5198, 5462, 6023, 6413, 6529, 6642, 6692, 6784, 6868, 7002, 7031, 7046, 7111, 7138, 7163, 7179, 7221 ex RB(wooden) 762, 770, 821, 942, 3737, 11180, 11188, 11200, 11207, 11223, 11240, 11242, 11248, 11249, 11254, 11256, 11258, 11267, 11268, 11274, 11286, 11290, 11302. Ex RB(steel) 715, 776 ex RBT 759, 6813, 7163, 7221 to QRN
1972	804, 942, 4232, 4274, 4311, 5198, 6692, 6985, 7031, 7072, 7136, 7179, 7232/7, 11248, 11268, 11274, 11286 to QRN 759, 804, 942, 11248, 11268, 11286 ex QRN
1975	790, 11223, 11261, 11265, 11290 to QRD
1977	7111 written off
1990	776, 11207 written off
1992	804, 942, 5162, 6413, 6506, 6642, 6875, 7239, 11240, 11248, 11254, 11302 written off.