Buy some cheapazoid thing to drive, and start pulling parts!
Mechanically inclined or not, I'd be studying that diesel, to answer some questions:
How do you check the glow plugs?
How do you change the fuel filter? Where can you get them?
What kind of block heater does it have?
What weights of oil are recommended?
Is the pump timing changed by vacuum/rpm/fuel pressure?
Can you/how do you change base timing? (On mine the word was to advance base timing by 1 degree every 75,000 miles or so, to adjust for wear)
Is there an inline heated fuel pump?
At what rpm is max torque?
...and so on...
You don't have to be the one that does all that work, but identifying parts and what needs to be done saves labor hours, since a mechanically inclined friend can help with the "doing."
Find out what the particular weaknesses of that engine are, and be proactive in controlling problems. Sure saves money down the road...
Now as for what to physically do next, that's tougher. Not knowing all of the situation, I'd say just pretend that it's an electric motor, and that you have to make it fit in your truck. Maybe to help visualize, you could start pulling non-essential parts off of the Benz, to help make things more accessible, and selling them on CraigsList!