Have you tried using cyl pressure to pop it out? You don't have a lot to lose, and it shouldn't fall down in there at this point. Intake stroke will have no real suction, so you're pretty darned safe.
If I were in your shoes, I'd even go so far as to start the truck up if it didn't pop right out - get those cyl pressures /way/ high and it should come out sooner or later. Of course, you'd want to put something in front of where it comes out so it doesn't put a dent in your hood or anything.

 

He did that already, said he even drove it and it didn't come out.

Heads can be done in-frame, but they are not easy as they are heavy as hell and the rear bolts interfere with the cab on the lefts side, and the HVAC box on the other.

 

Out side of the box and slightly insane idea/theory, how about filling the cylinder with oil and crank the engine by hand or bump the starter? Hydraulic pressure would be way higher and mite pop it out
worst case is you have to suck the oil out and pull the heads to get it.

 

If it won't come out with actual engine ignition, I don't think it will come out trying to crank by hand. But hell, if he wants to give it a shot and it works, who am I to say?

 

Because you might bend a rod.

 

Reading this thread has got me worried and thinking. Even though my truck starts fine, should I think about replacing the glow plugs before they get bad to avoid this problem that elenorzx is dealing with? I had bad ones in my old IDI and didn't have a problem when I changed them but I shutter to think about having to pull the heads on a motor that has nothing wrong with it.

 

You won't bend a rod with the power from the starter, that or by hand. It's barely enough to move the thing as it is!
If it tries to take off, however...


That all being said, here's a thought:
Is there a reason you need to get it out?
Keep a spare GP, 3/8" deep socket and wrench in the car with you -- what you'd need to install one if it ever comes out.
Electrical tape the 8th GP wire up, and just drive it. Worst case, it'll pop out on you sometime as you're driving down the road(or, probably, lugging it going up a hill, when cyl pressures are highest). Or it might just not come out.
You might have some trouble starting due to the GP controller being confused, but if you don't want to spend the time and money pulling the head(big job), you can either rig up a push-button, or take an extra GP and just attach it somewhere on the engine where it can't do any damage getting hot and hook it up -- so the controller has the extra load.
7 working GPs is plenty to have the truck start in cold weather, and warmer is even easier.

 

I think this is what I would do, with heat and pressure I'd think a good chance it will come out eventually.