The history of my car shows it did the head gasket at around 120k - this was before I bought it. I have no idea why it went as I did not have the car, but it shows up as having been done.
As for the motor being indestructible - mine was pretty tough for the 120k I put on it before swapping over for the 4.0 donk.
Pretty much I busted hoses on it three times - and each time I was running on gas which saved me (b4 anyone asks - this is because the mixer system on the gas requires coolant to be circulating and stopping the gas/system from freezing up. Bust a hose, no coolant, gas system freezes up, motor can't run because no gas).
Having said that - the motor got very very farking hot all three times and it pissed coolant (or whatever the hell is was - it looked damn nasty - almost black the shite was) out all over the place and here I was nearly in tears thinking I have cooked the ol' girl and.......
New hose - let it cool down and lo and behold it kicks over - not seized and running fine and still went along without missing a beat. Before going through this, I thought the 3.9 motor was not the strongest. It may not be the strongest, but after mine went through what it did and still loved hauling arse - I definitely have a much healther respect for the strength of the ol' 3.9.
btw - don't anyone bag me about the state of the cooling system on the old motor. I did so much work to that sucker including all new hoses, flushes and even pulling the tanks off the radiator and so forth....