YZ class were mainly recoded from _BD_ in the 1910 recoding. Some vans were converted into the class in the late 1900's. The number group was 1 - 69.
In 1922, YZ 12 was converted to XYZ_ 14.
By the 1930's, the only vans left were stationed at loco depots on 'Breakdown trains'. One van survived as a railmotor trailer in the Mallee district.
The YZ number group combines the codes YZ and YZH. The YZH vans were recoded from BDH_ vans in the 1910 recoding. These were vehicles removed from general service due to age and were placed into limited traffic such as for holidays or special excursions.
There were only two YZH vans: numbers 43 and 67. The last car YZH 67 was removed from service in 1913.