These ten wagons were converted from classes GM and GH. They had no side doors and were intended for unloading via tippler. Although I do not know of any written record that shows that GHC18634 was reclassified to GH, the photo clearly shows the "C" painted out. Details of the class are given below:

1975	15956 converted from GM
1976	18407, 18618, 18634, 18665, 18666, 18737, 18772, 18844, 18849 converted from GH
1985	18772 written off
1986	18618 written off
1987	15956, 18407, 18665, 18666 written off
1990	18849 written off
1992	18737, 18844 written off
	18634 unaccounted for but see photo