Diesel Bombers - Duramax Blues

This is my first diesel truck and maybe my last. I presently have a 2002 lb7 with 170,000 miles. In 09 with 130,00 miles, I had white smoke at idle and was told by dealer that I had two injectors bad. He also told me my truck was 3 months over 7 years old so it did not qualify for the service bulletin free repair. SOL huh? So I had an independent garage replace the two injectors acting up at the time. Fast forward to April of this year. On my way back from Florida , my crankcase filled with fuel. Took it to a mechanic who said I had an injector hanging wide open and all of them should be replaced. So I had it done there. They also said they installed new cups. When I picked it up, it made a hammering noise on acceleration. Mechanic said it was probably a bent rod or rod bearing. So I drove it home the rest of the way. Took it to a Chevy dealer here at home, and as soon as he heard it , said it was injectors, NOT a lower end problem. So I took it back and told them what dealer said. After rechecking the return rates and something else, they agreed and took them out and sent them back to the reman place. A week later I pick it up and the hammering is gone but now it is using coolant and the low message is on no matter how much coolant is in the recovery tank. So I replaced the recovery tank hoping that it is a sensor issue, but it still comes on all the time. I can loosen the cap two or three days after it has run and the tank still has pressure on it. I can release the pressure then on start it up, it will perculate and build pressure again quick. The tank I took out was kind of discolored also. It also exhausts light colored smoke at idle again.
I know this has been a long story but I just want someone to know the whole scenario. Now the 60 dollar question..... Do I have a cup problem along with an injector problem? I am trying to get informed so when I go back I can at least know what I am talking about. Thank you in advance to anyone who can help me.
Mike