Yes turbos and piping are extra failure points. But they also allow much reduced size and weight of the engine. Together with better fuel economy.
A 6 cylinder non turbo diesel will be running at cruise near BSFC of 300g/kwh
A 4 cylinder turbo diesel with similar power and torque will be around 220g/kwh in the same conditions.
Over 30% difference in fuel economy.
The 8.2L Isuzu is in an 8 ton truck because that's the chassis size you need to fit an engine that size. A previous employer had one, the engine is huge. Long and tall. Sure aluminium will make it a bit lighter. But it won't make it smaller.
Gardner or Albion? Both long gone. But specs aren't impressive:
Gardner 4LW, 75 hp @ 1700 RPM, Natural 4-cylinder diesel, Cylinder Capacity: 5,580cc
Gardner 6LW 102 hp (later 112 hp) @ 1700 RPM, Natural 6-cylinder diesel, Cylinder Capacity: 8,370cc
Gardner 6LX, 150 hp @ 1700 RPM, Natural 6-cylinder diesel, Cylinder Capacity: 10,450cc
Gardner 6LXB, 180 hp @ 1850 RPM, Natural 6-cylinder diesel, Cylinder Capacity: 10,450cc
Gardner 8LXB, 240 hp @ 1850 RPM, Natural 8-cylinder diesel, Cylinder Capacity: 13,933cc
My ideas don't really revolve around the outback. Conditions here are very different. Altitude and cold are more common than sand, still have major problems with heat in summer etc:
3-4 litre 4 cylinder diesel, compound turbos.
6sp manual with two speed transfer.
Fulltime 4wd with torsen diffs in each and centre diff lock.
Traction control standalone from brake system.
235/85R16 tyres (several sets).
Webasto diesel heater.
Tinted double glazed windows.
Heated seats, mirrors and front/rear glass.
10kw of AC should cover it.
Worklights all round.
Air over hydraulic suspension.
Quite different to an outback truck, but for quite different places.

