Yes, as you suspect, the diesel era put paid to all of that. As you say, certain locos were in steam days very much associated with certain lines, although classes like J15s could end up all over the place. In diesel days, Inchicore was Planet Central. Even the G611's got about - all but one of the seven were to be found in Loughrea from time to time (the missing one, G614, probably DID go there too, but I haven't seen a pic of it). E's were probably more static, though, as all here will know, while they're primarily associated with dublin, they did turn up at other places, sometimes (like Fenit, Shelton Abbey at al) not where you'd expect to have found them. (I personally saw them in Cork and Limerick - the latter, I think, E425 in the mid-70s).