My 98 2.8 liter 6cylinder TD Intercooled GU Patrol has factory fitted twin diesel tanks.
Main tank 95 liters, aux 35 liters.
For extra power and better burning of diesel, have LPG fumigation fitted, tank holds 35 liters.
LPG injected is anywhere from 0% to Max 16% at full throttle settings.
The gas fumigation has increased the HP from the factory rated 90 to 120, an excellent result, well worth the expense.