Don't have the part # in front of me, but our Comp rollers in our stroker 340 have cracked in several of the bodies. Roughly 53 passes on the combo. Not sure why, moderate cam, decent spring psi, no "at the moon shift point" (6700 iirc...) good pushrods. A strange harmonics perhaps?? who knows. I'm quite certain we're going to give the ones Brian has a try though.