JXA3696 and another unidentified JXA (Photo J Moir)

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, 1915, 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.

A group of JXAs at North Fremantle blown up from a State Library of WA photo.

From 1967 the JXAs were written off as follows:
1962	877, 922, 1464, 2369, 2372, 2459, 2497, 3056, 3663, 4128 modified discharge pipe and bolster
1963	525, 1144, 1910/3/5, 3696, 3704, 3881, 3994, 4110 modified discharge pipe and bolster
1967	3994 written off
1968	1144 written off
1970	1910, 1915, 3056, 4128 written off
1976	525, 922, 3881 written off
1978	877, 2369, 2459, 3704, 4110 written off
1979	1464, 1913, 2372, 2497, 3663, 3696 written off

The WAGR outline diagram is shown below. It misses the footboard along the top of the three bolsters.