...well, the 1649 anyway.
A great aeroplane.
Prop synch was normally done by the flight engineer, as he (only) had the prop controls at his station.
On the DC6, the pilots were indeed able to do this, and it was all (usually) done by ear...with lots of practise, if the prop syncho was unserviceable, which was quite a lot, in my experience.
Start with number one, and work across, in sequence.
Lots of fun....
