That is some right impressive carnage cougar!
So, I have to know: clutch dump in 4x4? bottom out front D-shaft slip yoke? T-case parked on a rock? or, sled pulling!

I would have a real hard time believing that was a power induced failure.
Unless there was waaay to much, or waaay to little preload.

Or, you were hooked to the sled, pouring some serious torque through that box.

 

I have 3 Getrags.

The one from a D250 (375,000km) going into my Ramcharger is flawless. Overfilled with 5w50 synthetic.

The one in my W250 (335,000km) is getting sloppy. Doesn't go into 1st gear very nice. Has a rattle when lugged in 4th and 5th. 3rd gear synchro is starting to go. Since I have some extra power in this truck, I try to match revs better when I shift, and use more revs in general - seems to like that better - and still drive it almost every day. Also overfilled with 5w50 synth.

The one in my other D250 (320,000km) is getting hard to drive. 2nd gear synchro is shot. 3rd gear is hard to find. Will pop out of 4th and 5th when you come off skinny pedal too quick. Seems like its guts 'travel' forth and back in the case. I suspect massive endplay on the bearings. Makes a horrible sound sometimes when clutch pushed in... release bearing?

IMO, it comes down to how you treat the trans, and being aware that turning up the fuel on a cummins with a high-mile Getrag and beating on it is probably a recipe for disappointment.

 

I wish it was something else.

 

OUCHIE!!!

That explains it though. Bottomed the front D-shaft slip yoke.

 

looking at your photo bucket pics....

Pretty harsh that it broke the iron Getrag case, AND the iron np205 input housing!

 

AND the 205!!!! go check the pics again. The 205 itself is in pieces.