Quote:

Rick Ehrenberg says it was from the consolidation of the AMC engineers when Chrysler bought AMC/Jeep in the 80s. When the 5.2/5.9 magnum was being developed, the AMC guys insisted on the pedestal mount design.



This is probably the closest to the truth of it all. The Magnum head incorporates some runner designs that are more closely related to the AMC heads than traditional Chrysler small block heads. How else do you think they improved flow, swirl, tumble, and reduced chamber volume. The original Mopar small blocks heads were pretty crappy to begin with so why not clean sheet design them with the ideas form the AMC group. The icing on the cake was now they have a greater parts interchange with other engine families as well, so while the cost per engine may not be significantly less than the shaft system, the cost of ordering ten of thousands of rockers for engine builds over a decade adds up quite a bit.