12v or 24v vp rods are the rod of choice if your going to shot peen harden a rod due to them being forged(1st/2nd gen 12v-2002 24v Vp will bend) and not cast with cracked cap style rod caps(03+ Commonrail will break into pieces). I have a set of England Vp rods I was going to harden and run in my 06 but heard a commonrail will bend a rod as easy as breaking one so I bought billet instead. And a 6.7 will bend or break one easier also due to the longer stroke Meaning an increased crank angle on the rod. It's all about your setup, power goal, and what the truck is going to be used for. I broke a factory rod in my 06 at 800hp but made 1800ftlbs of torque due to my compound setup and making my power down low. There is people out there making 1000+ on factory rods but making there power higher in the Rpm band(larger single or larger compounds). Hopefully others will chime in with more information.