loss all gears in transmission?

So I need more information and short video will help me tell for sure what is going on. If the rear end is broken the transmission will grind when putting the truck in park is this what is happening? Or does it grind when in gear but not move? Please let me know so I can help you. If the truck does not move look under the truck when the grinding is going on to see if the driveshaft is spinning, this will help us. Ken