Pretty sure the fg637 has the same running gear.
Oil Type: Castrol J Max 15W40
Ash 1.5% or higher
Class. CD CE CF4
Capacity. 8L + 1L filter
Gearbox
MO35S5
Transmission. 3.4L
API CD
SAE 30 or 40
Transfer. 3.0L
API GL-4
SAE 90
Axle Front. 3.0L
API GL-5
SAE 90
Axle Rear. Limited Slip Diff 2.7L
API GL-5LS
Power Steering. 1.8L
Auto Transmission Fluid
DEXRON II type
Coolant. 13L
Notes:
Diesel Filter P550049
Fleetguard FF5088
Rear Diff LSX90
Front Diff EPX80W90
Gear Box Castrol TFC450 SAE50
Oil filter (FleetGuard LF3830)
RYCO Z372
Air Filter AF409KM
Or Donaldson P182054pointhk