2002 Tundra 5 speed 3.4L

My son was driving along and heard a very loud bang. Now the truck will roll when out of gear (5 speed manual) but when in gear it's as if the rear end is locked up. My rear end is the standard rear. What is it? Do you think its the tranny or the rear end?

I pulled the rear end and the spider gears and center pin are in pieces. Off to the rebuild shop!