Just to be clear:Because the pistons are smaller and presumably lighter on the "44" vs. the "49" do the crankshafts and/or flywheels differ for balance reasons?
1) The crankshafts are different on all three models (44 Commercial, 49 Commercial, and 49 Vanguard). As far as I know, of these only the Vanguard is forged.
2) The pistons have different stock numbers on all three models.
3) The flywheel is the same on the commercial 44 and the commercial 49. The Vanguard flywheel is different.
I don't know about the balancing of the crank and other rotating bits (pistons, rods, etc) using the flywheel. If they did that, then replacing the flywheel would require a new dynamic rebalancing of everything.
I'm not sure why the Vanguard 49 requires a different flywheel from the others.