Hmmm....I was told by my dealer when I bought the Ironman that Isuzu's warranty was for 7 years or 70k on the powertrain. Who knows for sure...Dealers have lied before.
If I was in your shoes Capt. I would investigate the "replacement" Direct Injection motor (3.5, 250 ponies vs 215).
I would be very interested to find out what actually happened with your motor. Can you post when you find out what caused the blow up?
Good luck
John