Green’s Dictionary of Slang

1. a large sum of money.

c.1698		B.E. Dict. Canting Crew.
1725		New Canting Dict. n.p.: cargo, a handsome Sum of Money about a Man. We got a good Cargo from the Cull, i.e. We plunder’d him of a great Booty.

2. a thief’s or pickpocket’s takings.

1734		C. Johnson Hist. of Highwaymen &c. 118: All this Cargo to be brought Home [...] by two little Rogues, so young, was, it must be confessed, extraordinary.
1901		W.S. Walker In the Blood 159: You pinches yer cargo off ’em in the early mornin’.

3. (W.I./UK black teen) a heavy gold chain and medallion sported as an outward (sometimes pretentious) show of wealth.

1992		V. Headley Yardie 68: ‘Cargo’ – the thick gold chains and medallions which are the outward signs of success.
1995		Francis-Jackson Official Dancehall Dict. 9: Cargo heavy gold chains with or without huge adorning medallions.

4. a purchase of alcohol or a measure of alcohol drunk.

1937		M. Pellew Dead March in the Desert 194: ‘I’m not movin’ [i.e. from the canteen] yet,’ said John. ‘I ain’t got my full cargo aboard’ .
2020		G. Armstrong Young Team 5: It wis stolen beers fae yir maws n das [...] Noo, we’re out gittin proper cargos wae the troops.