Green’s Dictionary of Slang

dustman n.¹

a corpse.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Dustman. A dead man: your father is a dustman.
1811		Lex. Balatronicum.
1859		Matsell Vocabulum 29: ‘Poor Bill is a dustman; he was a bene cove,’ poor Bill is dead; he was a good man.
1881		Trumble Sl. Dict. (1890).
1895		Crowe Aus. Sl. Dict. 26: Dustman, a dead man.