Earlier, xxxxlbear mentioned PBR, and that railway is indeed worth a look.
The NA's all have turbo generators and electric lighting - that is a modification from the original kerosene lamps.
The NA's also have "remote control" greasing points - a lot of grease nipples mounted externally, carrying grease to hard-to-reach places - that is another modifcation.
They all have steel cowcatchers, when the originals were wood; 8A has the stovepipe chimney; 14A has an all-welded boiler, 6A has a modified front end, and so it goes on.
They show railway progress over the years, and that, in itself, is history.
Just one thing I'm wondering...what parts of the NAs that are currently running are still the original parts from when the locos were first put into service? Be just the frames, driving and pony wheels and some of the rods? I know that poor old 3A was cannibalised to keep some of the others going. What is actually wrong with 3As frame for it to be no good? Wasn't 12A's fame restraightened at one stage? Where do i go on faecesbook to have a look at this "discussion"?