no. the rear diff is 3 quarts of severe. might be a little less than the full 3. you want to fill it just below the fill point. the bt-50 manual outlines the correct measurement.
the front and centre diff. and gear box should take the next 4. approximately.
I can't remember the measurement for the gearbox. i don't have a manual anymore, but you should have the measurement in yours. be sure to look under the correct region.
use the same amzoil 75W-90 light duty (clear bottle) for the gear box as well. i am looking at my maintenance records but i didn't have the quantities listed. sorry. just double check the quantities. i find amzoil has worked really well for me in the past, i am axtually going to change out to everything amzoil on my hilux whenever i have to change a fluid.
if you are at your 40,000 km service or even if you aren't, i strongly suggest that you grease all 3 crosses underneath your van. are you doing the service yourself? the ones on the 4wd case and the centre diff. are fairly okay to grease. be sure to pump grease until you see new grease exiting all 4 lobes. on the rear diff. you will have to roll the van back or forth to line the grease nipple up correctly so that you can snap on the grease gun. it might be difficult as mazda did a proper shitty design with that nipple.. once you get it in, make sure and fill this with grease. it'll be your first to go due to the fact that it is difficult to get the grease in and most people, mechanics, ssl and otherwise don't ensure that all 4 lobes are full. sometimes you'll crack it and find one completely dry because once it gets plugged the first time, every other time you try to grease it, no grease would get in.
i use castrol pyroplex blue, NGLI2. i guess any good heavy duty grease would work, again, double check what is recommended in the manual. i am sure the castrol is safe.
hope this helps.