Normally Aspirated 337 STC's

[kevin]

I don't really think there is such a list. It would be interesting to compile one, perhaps I will start a project to do that soon. You can get an STC list from the FAA, but it is very difficult to decipher which ones are available, and from where...

Meanwhile, the only engine replacement STC I am aware is available from Riley, now called Skyrocket LLC. (http://www.superskyrocket.com/). They will put 540's in for you.

Kevin