02 Dodge 3/4 ton drive line

My co worker and I just came across a traffic hazard. On the great river highway in St. Cloud, MN
(9th Ave North-- 4 lane at that spot) a nice looking dodge PU was stopped at a 20 degree angle making a right turn. The owner was under the truck pulling the drive shaft out from beneath. It had landed directly under the truck. The transfer case lower rear section, including the silent chain driven gear, and a spur gear and the lower shaft were attached to the yoke in a puddle of oil. The rear of the drive shaft included the joint, and splined pinion yoke.
We attempted to help by parking and giving a push assist to the side street he was turning onto.
three of us pushed (neutral and brakes off)
As we pushed hard, the truck maybe moved 3 inches forward against what seemed to be spring windup. when we let go it went back to where it was.
The transfer case, where the rear shaft comes out was twisted off entirely with 15 pounds of the gears hanging out to the front.
The driver said there was no warning or noise from any thing just a radical Bang, and a 5mph to zero stop in one foot. (no skid marks)
What are your thoughts as to what happened?
Jim

Something broke.

I would say that the pin in the rearend that holds the spider gears let og and locked everything up. Happened to me oneday . Dropped the drive shaft pulled the axles out locked the hubs in and drove it home . Ah the good old days of CAST IRON NP 205 transfer cases Bullet proof. Pulled here apart and replaced the pin and lock pin and was back in business in a couple hours . But not for that guy he is going to need some shell we say pieces and parts.

I've seen this a few times at the dealership. The transfer case locks up. It seemed to be only the Nu Process 241 or 242. We never figured out why, just replaced the unit and never saw the vehicle again. The one's I saw were Durango's.