The ability to find something on Google does not always represent reality. Isuzu diesels are nothing like a Duramax. Cummins will carry some parts for the engines used in combines, pumps and generators. Dodge Rams are not exactly the same. The most common problems with diesels in PU's are fuel or emission related. The Mexican emission systems are totally different. Don't know about the fuel system. I would not go to Mexico expecting that parts are everywhere. If you are lucky and find something: GREAT. Today's dealerships use a computer tht is connected to the Mfrs. mainframe. The software resides in Mexico city or maybe Monterrey. If your vehicle was never sold in Mexico they usually cannot access the info. The ECM's are totally different. Any decent shop can read trouble codes but that is only a diagnosis not a repair.
Moisheh