Just a thought and it might be way off, but I live in Washington and use the Street Shuttle services and I would say from personal opinion the M2/M3 needs bigger buses. But the W5/W6 doesn't tbh, only gets busy at peak times. And Washington normally have a Northern President or 2 on the W5/W6 anyways.

So although everyone is saying the Street Shuttle is getting the Saltwell Park/Drifter Versas, I think it may only be the Saltwell Park ones for example, with the W5/W6 staying MPD operated. With 8319 also going to Washington as a spare.

Which would then lead to the Drifters going onto the 39 once the Streetlites arrive. Hence why 547 has been painted Northern. I can't think of any other alternatives as to why GNE have done this.

Plus on top of that you have 5 spare Simplicity Versas due to the changes to the 36/36A and then you have the Street Shuttle MPD's and possibly the Doxford Clippers MPD's if what i've said above happens.

Then on top of that later in the year when the 20/56 and M1 get new buses your going have roughly about 40 Wright Solars become available for other services.

Anyway whatever happens it's certainly going to be a very interesting next couple months for us as enthusiasts and GNE.