Plus (possibly)

Pistons(different or installed differently)

Con rods (Weighted or balanced differently)

Dynamic balance weights

Balance dampners
Accessories..

maybe more...

Dave





On Thu, 30 Nov 2006 17:35:55 -0500, "Capt. Geoffrey Thorpe" The Sea
Hawk at wow way d0t com wrote:

"Jim Macklin" wrote in message
...
The cost of manufacturing two versions of the engine and
recertification of the design is not worth the small
advantage. Most light twins were designed and certified
over 40 years ago.


What would be all the unique parts?

Camshaft has to be different.
Crankshaft probably is drilled differently for the oil passages.
Starter.
Oil pump.
Magnetos.
Vacuum pump, I assume?
Prop, obviously.

That should be about it?