Well, I'm sorry I had to give you the bad news prior to the bad news. But, there is good times ahead for you. This forum for one is the best and as you can see...people come to help. Now all you need to do is decided which way your going to go with repairs.
The thing I noticed to be one of the best things in preventing heads from cracking is to re-torque the head about 500 miles after installing a fixed or rebuilt head. Over heating is the number one problem of course for these issues and that is your number 2 things to do. Watch the temps on these trucks. If you see it climbing, pull it over fast and check for problems.

I heard a rumor about Mitsubishi years ago concerning the engine assembly and torqueing of head bolts from the factory. I'm not sure of any fact to this, but apparently when heads were installed on many Mitsubishi engines the rear head bolts were not torqued correctly. This was thought to be the main reason for numbers of crack heads and blown head gaskets in past trucks. Though the history I have seen with the trucks includes inferior metals and bad castings in many of Mitsubishi vehicles in the '80's years. One example are these darn exhaust manifolds that once were recalled for cracks.
Anyway, your not the lone ranger with your truck. We all have had the same thing happen to us long time owners as you have. I personally replaced the head 3 times and my 4th has been perfect. This might of been because I purchased a head without them MCA Jet valves. I just don't think the engine likes the burst of incoming air like that and creates a hot torch effect IMO.
Keep us posted on your fix, we can help with any issues you have during your fix.