That will depend on how the vehicle is used and what the manufacture recommends.
It could be as soon as every 20,000 miles or as long as 100,000+
Be more specific, Are you talking about the transfer case, transmission, or front differential?
once a week is recommended
You should get your floor machines serviced once every other year. They require regular upkeep in order to last a very long time.
Annually. If it`s fueled with oil absolutely annually.
The differential, often referred to as the "rear", is the gear housing which transmits the rotation of the driveshaft to the rear wheels. A four-wheel drive truck also has a differential for the front wheels.
Your fuel tanks are built to last the lifetime of your vehicle. They should only need to be serviced if they are damaged in an accident, or if some contaminant has been added to the tank.
Every 50,000 miles.
Every 30,000 miles
30,000
once a year, or 15,000km whichever comes first.
Inspect at least once a year, base service on what you see.
HVAC should be serviced about twice a year. I prefer service just before summer so I'm not left in the heat and just before winter so I'm not left in the cold.