..... and since we're on the subject of marker lights on 121s, this seems to be another variant with red lights on the cab end of 123 above the extant originals. Another great shot form Ernies archive just sitting at Limerick Junction for the day
https://www.flickr.com/photos/irishswissernie/15095259504/in/album-72157646594210844/
So when you consider the presence or absence of cab windows on the bonnet side of the cab, variations in the size of the main windows, lamp holders, marker light variations, and the grilles beneath the walkways on the sides, there's quite a lot to re-model if anyone is so inclined to do so.
Incidentally, I'm confused why it's been so quiet on the site lately. I'm assuming that there has been an unscheduled failure of the Irish cloud layer and an isolated sunbeam has hit the emerald isle causing mass panic in fair-skinned Celts,
....or Irish modeling is now entering summer recess?
Looks like 128 also had these additional lights on the cab end in 1998