brutal is the correct term.

Hmmm, every resource I've found says capacity is 2.6 litres for the gearbox LSD transaxle...

well... buy 4 just to be sure. and fill it till it pours out the filler port :)

They must have all been talking about the non turbo box

Nope, the turbo box.
Weird.
Anyway, I'll just fill it up and take note of how much goes in...

Yes, qutie confident in previous car (sw20 turbo with aftermarket lsd) 4 quarts was enough.  There is also a fill point you can use on the top of the gearbox which is easy to get to if you dont have the factory air box, using a funnel and hose.
 
Will see what the local shops have in stock of GL4 and get that.
 
Cheers

MR2QIK- Thanks for the reply mate but I've already put the 80w90 in the gearbox. Works ok, not hard to shift when it's cold. If I shift too quickly when the fluid is cold it'll grind going into third. This happened with the royal purple I had before but it's definitely better now. I think that royal purple may have done some permanent damage to the synchros. Gears shifted perfectly before I ran that oil. Wish I left it alone. No idea what oil was in there before. All I know is that it was red and worked perfectly.

Hmm I tried Redline MT90 from all the good reviews and it seemed fine. Felt good after change but might be placebo. Maybe I'm not experienced enough to tell the difference. Then again it was changed back in Jan/Feb and I haven't really driven the car since April. 
MR2QIK - it was unfortunate your box got stuffed from MT90. There seems to be very few bad reviews but mostly good which is why I went for it. Maybe it's not so good or maybe something else was at work?
One googling seems there was a bad review from Royal Purple too but a thumbs up for Redline. Because of this discrepancy, perhaps there are too many variables to have a definitive answer, me thinks. Time for me to shut up and go to sleep lol...

Adrian
All I know is that it was red and worked perfectly.

Could have been Automatic transmission fluid.

My friend had ATF in his turbo box for many years with no issues.
 
Cheers