Perhaps cuz there is a small sub set of our hobby that is reliving their past and building old skool combat planes and want to use the period correct engines. Or they just want (like me) to take their older engines and breathe life back into them for posterity sake.I have about a dozen older Fox combat engines mostly .36 MK IV and MK VI (no .36x) and would love Brian to do a run of P/C so I can gift them to my son and let him get 30+ years of use like I did flying VooDoo, Sneaker, Mongoose, Big Iron etc...