Now you have put a spanner in the works Rob....

Looking at the pictures I put up there...I have always called the one on the left a pilot shaft...and the right SG.

Now I know (after searching) that is incorrect terminology but you can see the reasoning there....the left hand engine needs an extra piece (pilot shaft) to use a clutch/flywheel....

Just another thing of confusion in the RC world...and we are only talking about a crank shaft...