I changed the front and rear differential this week in my ML320.
The only info I could find is 1.6 qts.

The rear took about that much, the front 1.3 quarts. I used Valvoline 80-90 durablend.

So I moved the truck to make double sure it was level and could not get 1.6 Quarts in the front one.

The Rear oil was golden. The front was thick. I ran a couple searches here for "gear oil", "capacity", "differential", and no luck.

__________________
Steve Danville
what i did myself.
CPS
rear shocks
MAS x 3.
SparkPlugs (twice)
Fuel pump & Filter
Window switch
replaced both failed horns with Honda horns.
Cleaned ERG Tube
Oil changes
Oil consumption Fix
Brake Pads
A/C Recharge
Anti-Freeze change X 2.
Front Shocks. Monroe. $90
Mercedes Warrenty Work:
Harmonic balancer,power steering clamp. Cat converters.Drive Shaft Bearing.s
Replaced Outer Lower Tie Rods and front lower ball joints at 156,000 miles