There must be something about the uniqueness of the C337 Skymaster that acts like a magnet to sound developers. Pilots of the type in FSX now have not only the original, but now two different sound sets available to replace it as well.
The name Oovee may be more familiar to our Rail Simulator using readers as they have created a number of add-ons for its various incarnations, but they have now made their soundset for the Skymaster available as well, demonstrated by the video above. For more information and to purchase the soundset, please visit the product page at simMarket.
The aircraft being used to demonstrate the soundset in the video is the Carenado HD Series C337H Skymaster, available here.