Longer vehicle

Can't see why you couldn't as long as it fits the ADR.

What you really need to be careful of is overloading the rear section and bending the chassis.

And once you have extended the tray does this mean you will need to move the tow bar back to make it accessible which again is creating more problems and the likely hood of more stress on the chassis.

From memory....
there is a ruling that :- the overhang behind rear wheels cannot exceed more than 40% of wheelbase.
I believe this to be so for trucks thus carried over to light vehicles
Murray

If 40% of wheel base, for a 3200mm wb means 1.28m MAX rear of rear axle centre. That is a long way out.

The overhang behind the rear wheels allowable is actually 60% of the wheelbase, or 3.7M, whichever is the lesser measurement.

So that means you probably can fit a single cab tray to a dual cab.
But the average single cab tray is 2.4M long, while the average maximum length for a dual cab tray is 1.6M.

The extra 800mm is going to stress your chassis an enormous amount, and I personally, wouldn't recommend the fitting of a 2.4M tray to a dual cab.

In addition, a very long tray such as you are thinking of, will seriously affect vehicle handling when loaded, causing vicious oversteer, if you do even a mild swerve.

Google "bent ute" and images, and you'll see plenty of examples of bent chassis' on dual cab utes, that generally have a lot shorter trays than 2.4M.

Excessive ute tray overhang discussion

Cheers, Ron.

Going on the numbers posted, I reckon you'll just about halve your load carrying capacity on the tray if you add another 800mm behind the axle.

Gusthebus,

I must have been the only one to have seen you say you're not worried about the weight distribution.
Measurements aside, make sure rear light assemblies and numberplate are at the rearmost of the tray, and can be seen from all the angles specified.

And be wary of end swing.

Gusthebus So your wanting to put single cab tray on a Extra cab ( Not twin cab ) there's not a huge difference in length maybe 400mm
At least that's was the differents from my old SC triton to my super cab ranger .
It would be a big help if you gave some sizes for people make a proper judgment .
and even explanation of why you want to do the change . obviously there would be some problems if the a tow bar on the vehicle .

Thanks all for advice so far. A mate is doing it and i saw it for myself today and can't believe it's legal but cant find any indication that it's not.. Obviously weight distribution is poor-yet legal?

G'day Gusthebus, I have a single cab Dmax with the 2600mm tray. There's 1340mm from the centre of the rear axle to the back of the canopy and I have a tool box behind each rear mudflap, spare wheel and towbar.
I'm not prepared to put any more weight behind the rear axle and I don't tow anything.
However some single cab trays are shorter than 2600mm so you may be OK.
I live in Cairns and you're welcome to have a look at my ute if you're interested.

Overhang? what overhang? Canadian camper.

The legal limit looks less than you might imagine sometimes.

Cheers,
Peter
OKA196 motorhome