What makes you think the injector bodies are cracking? Under stock power levels, a sensor failure aside, cracking the bodies is rare. Mor eoften than not it is wearing the pintle seat and the injector is never sealing. That sis a constant stream of fuel into the cylinder which melts the piston and fills the crank with diesel.I may not be very bright, but I just can't figure how bad fuel can make an injector body crack open.
Your fueling habits are suspect. NEVER fuel at Walmart of grocery store, thats a secondary line to them and you will always get 2nd rate fuel.
Either go fuel at truck stop at the truck pumps or find out where the local sheriff and EMS units fill their trucks and patronize that station. Those guys will generally know who has water and dirty fuel problems.
If you want to run suspect fuel you need to add better filters and water seperators than the OE. The OE filkter has some of the best water seperation capabilties there are but the 7-10 micron is not good enough to stop injector wear. You need a 2 micron absolute just in front of the CP-3 to be safe. While your at it, a steady diet of 2 stroke or 10wt non-detergent oil mixe dwith Power Service will do a lot to keep your injection system healthy.
Its not the 05 injectors, its the fuel that is the problem. I have over 180k on an 05 with ZERO injector, mileage, start, run, etc, problems. I fuel at high volume stations where EMS and law enforcement does, or truck stops frequently on the truck pumps, and use the oil\PS mixture.
My cousin bought an 05 Durasnack at the same time I bought my Dodge. I had 40k and he had 5k a year later and he was stranded for a week waiting for an injector replacement. He has had multiple issues with injectors before 60k. Garbage in, garbage out. Keep feeding the Dmax that way and it will come back to bite you.