When the W.A.G.R. stopped providing passenger accommodation on goods trains the ZA and ZB class vans were made redundant. Unlike their smaller ZB class cousins only one of the larger ZA class vans (ZA192) was converted into a Z class brake van (in March 1969). It is assumed that the experiment was not a huge success. Z192 was written off in November 1977 although it was used as a storage van for several years after.  I don't have an outline diagram for this one but the position of the remaining doors and windows seems unchanged from the ZA it was converted from.