In 1958 six 1500 gallon J class water tankers (1144, 1464, 1913, 3881, 4110, 4128) were converted to carry bitumen. This conversion involved raising the tank at one end by ten inches compared to the other end to encourage the bitumen to flow out when discharged. A further fourteen wagons followed in 1959 (525, 877, 922, 1910/5, 2369, 2372, 2459, 2497, 3056, 3663, 3696, 3704, 3994)

 In 1962 the discharge pipe and bolster support was modified on half of the wagons with the rest being dealt with the following year.

From 1967 the JXAs were written off as follows:

JXA3696 and another unidentified JXA (Photo J Moir)