Merlins were also used in civilian aircraft.

Canadair Northstar was a DC4 with Merlins instead of radials.

The last surviving one is in Ottawa Ontario at the the Canada Aviation and Space Museum.

I delivered an ornithopter to them some years ago and got the back room tour of the place. I can say I helped with the restoration of this aircraft. I held one of the magnetos up while the tech removed the bolts to get it off the engine. Lol.

https://en.m.wikipedia.org/wiki/Canadair_North_Star

Kevin