Do we already know whether there will be special timetables on the route? Something like the museum train on East Coastway. A Class 66 was briefly seen in the stream. Does it belong to the SEHS route or does it come from the EastCoastway / GWE. Unfortunately I couldn't see the whole stream. (Sorry if anything is wrong here. I use google translator)
From what i remember from earlier in the stream: The class 66 is linked to the East Coastway route. It will run 1 freight route to begin with, and there will be a couple of Class 66s parked up in sidings that can be used for shunting in free roam. (It was mentioned that in a future update more services will be added). Northern Transpennine will unlock heritage tours: 4 timetabled journeys, 2 in each direction. I think but am not sure, that trains from Tees Valley and West Somerset can be substituted in.
I know that it said the rail tours trains come as layers from their respective routes but I’m not too sure on the class 66, I would say it’s best to assume it does come from ECW unless they confirm otherwise
They confirmed on stream that it will use the ECW variant, and you will need ECW to use the loco services, along with NTP to provide the passenger rakes.
The class 66 has a multiple livery selection on it so it could be possible to use only the great western express add on
The GWE 66 and ECW 66 are as far as the game engine is concerned different locos, not interchangeable (well, except by bug....) Like the RT and SKA Talents.
The GWE Class 66 may be able to substitute in but you will need ECW for the actual services to be there, as that is the specific Class 66 they use along with the wagons from ECW. The Class 66 variants in GWE are a different model (3D model rather than model of train).