The original magnum r/t heads p5007140 and 71, etc, were proprietary MP parts.

The P515-series are called "magnum r/t" in the marketing materials, however they are 100% an enginequest head which Chrysler has not done anything to at all. I don't even think the packaging is different. Note, my information is from 2013.

I didn't agree with that decision but that was two jobs ago, and at the time the powers that be weren't having it any other way.