Spec from FO-44 shop manual. for 1900
I think this is the gear box you are refering to.
front Axle reduction case (each) .22 L (.23 US Quart) more capacities
Front Axle differential case 2.4 L (2.5 US Quart)
Coolins system capacity, 6.8 L (7.2 US Quarts)
Crankcase* 5.5 L (5.8 US Quart) with filter change, 1700 only={4x4 .5 L or .53 qt less}
Fuel tank, 29 L or 7.6 US Gallon
Transmision, rear axle & hydrolic system: 24L (25.4 US Quart)
Don't forget to greese the hubs.
There you are, if you need something else just ask.
Ray I.