Originally posted by Steve Holmes
Here are some NOS Ardun heads sold by RM Auctions in 2009. These heads sold for US$26,000! RM Auctions description says there were actually thought to have been no more than 275 sets made, so ever rarer than I thought.
Ardun heads were also available for the smaller V8-60 engines...

There would no doubt have come out in even smaller numbers, but eventually sold in the many thousands as they were adopted by Chrysler in South America for the Simca-derived Chrysler Esplanada engines in the sixties.