In a long ago issue of Mopar Muscle, there was a side bar editorial called "Steves Stuff" with Steve Magnante. He had one or two of these of these and also stated a production number of four. These were a prototype of a planned production change in the magnum production engines but was scrapped when development of the Hemi started. I myself feel we gladly could have done without the gen three for a good five or ten years just to have access to factory aluminum blocks.
