The AUS NB1 Quartermaster Cab Chassis (base trim) Petrol has a kerb weight of 2,446kg & the Diesel has a kerb weight of 2,527kg both including 90% fuel tank & all other fluids at the correct level.
The total gross weight of both versions is 3,550kg
Higher trim levels do have a higher kerb weight. E.g. Trialmaster with dual battery, tow pack, additional wiring, RAI, KO2 tyres, diff locks, smooth pack, all adds approx. 100kg.
So with load capacity is 1,104 kg & 1,023 kg respectively with 81 litres of fuel.
Most manufacturers either don't include the fuel or don't state if it does or not when they quote a kerb weight.
So if you add a Norweld canopy & tray at 289 kg and the extras for Trialmaster spec at 100 kg that still leaves 700 kg & 625 kg respectively.
Logic says you would add an extended fuel tank at the same time.
View: https://www.youtube.com/watch?v=ioBdOioXsV8