How it happened or why it happened?
The 'how' was descending a fire-road and dropping into a small washout at the bottom.
The 'why' is a four part puzzle.
#1 - the front drive shaft was too long.
#2 - there was only one mount on the rear of the 203 and nothing on the 205
#3 - the shift rails in the 205 had been ground incorrectly which was allowing for cross ratio shifting between the front and rear axles.
#4 - the th-400 wasn't a 'K' series case, stock tranny from a 2wd.
Repairs made:
1) shortened the front shaft
2) fabbed up another mount to support the rear of the 205
3) already having the doubler out was a good thing, pulled it apart and sent the rails back to ORD for another set. (couldn't save the original ones)
4) a local th-400 guru built me a stout new tranny armed with the full knowledge of what the truck was going to be used for.
All tricked out for hard wheeling, including compression braking that would rival any standard tranny out there.
So the story is, take your pick...
Could of been any one issue by itself or all working together.