OK. Now the awd 5MT EA DR is in my EA82 'powered'  Brumby it will surely use more fuel

Anyone have documented experience of similar gearbox only change?

I cant see why

There is no new load on the engine.

In the pt4wd the engine torque drove the front wheels which pushed the vehicle, and the moving vehicle made the rear wheels turn which made the rear diff and tailshaft turn

Now the ft4wd box transfers the engine torque between the front and rear. Same amount of rating metal (mass) and same amount of friction and losses (bearings and seals)

The only time running in 2wd saves fuel is in a vehicle with unlockable hubs, where you could drive without the front diff and driveshafts turning and wasting power/fuel

I noticed a change in fuel use but I put this down to running the wrong 5th ratio for the EJ, even though the diff ratio was matched to tyre size.

When turning my theory is that there's more friction in the centre diff doing it's thing.

Other than that there's really not much difference as mentioned by Gannon

Cheers

Bennie

I am certain I used almost one extra litre when I refitted the 36 kg worth of rear diff and axles n stuffand still in fwd function

So fuel saving was in weight and reduced rolling friction

ThenI upped the carb and converter size to bigger engine stuff ...tuned her in and got back to same as without rear drive bits

Now awd box is in feels a little tardy much like awd to rwd ford territory difference. Ratios may be different to before. 

Next chance I get will do comparison run

Results are in. Nothing changed about vehicle except box. Took it on same road trip 100 miles return as last week with part time 4 WD box in FWD mode. Same travel times give or take 5 minutes. Same traffic conditions. Same temps and driving temperament, same 10 dead ' roos and wombats in 10 metres

Used half a litre less fuel this time

Not saying it have any better consumption but it used to extra. Happy

Actually...it needed a new rotor and cap due to carbon brush burnt back into its orifice