In the case of 071s, there is a 121-esque issue in that they were delivered in a form of the livery not replicated on other engines, nor after their first repaint. they were in a very browny shade - not "orange" at all; this was applied in the States where GM obviously got the shade wrong. The black was the same. The CIE logo on the front was all white, instead of having white letters and a "golden brown" surround, and was somewhat larger than normal. After that, they were repainted in whatever the normal livery of the day was until their second "unique" livery of black and silver appeared. And by all accounts, they are all set now for another unique livery! A record?
The various liveries used since the sixties are generally descirbed as:
Black and Tan: Early 60s to mid 70s on various classes: orangey brown and black with upper white band. The orangey brown was variously full lower panel height, or a band lower down with a largely black side. Loco numbers on ends and larger on sides. 141s had no CIE roundel when delivered, though 181s did - and 141s later acquired them.
All Black: No, not rugby; a variation of the above from mid to late 60s (later on a few G's, D's and E's); all black but with white flashes above window level on ends only, though G class had it right round the top of the cab, sides and ends. At various times, and on various locos, logos and lettering on the sides varied; some versions had no CIE logo at all, others had the standard with orange surround and white letters. Loco numbers on ends in large version, and either mid-side large, or both ends lower side in smaller numerals.
CIE Supertrain: 1972-87: All over orange with broad black band equivalent to full depth of carriage window level, dipped or raised on ends. CIE roundel on loco ends only; white letters, orange surround. The delivery version on 071s was a corruption of this as described above. On the sides, loco numerals on both cabs at low level.
IR, or "Tippex" livery: 1987 - 1990ish; same as above, but with CIE roundel replaced by IR "set of points" logo on ends, and also appearing on the sides, mid black band. Numerals in same places, but white stripes (nicknamed "tippex" by some fitters in Inchicore) added separating the black from the orange at top and bottom of black band.
IE Livery: Same as above, but with "set of points" replaced by "Three Pin Plug" logo on ends, and by giant "plugs" on sides.
And here endeth the Orange and Black Era; welcome Enterprise liveries, apparently no two locos having an identical version, let alone when repainted; and both the original and altered colours; the green and grey of the "flying frogs" on the Cork line, and of course the hideous orange, black and yellow, with or without various sizes of yellow ends, as used on 201s from 1995. (Yes, I know; out of order chronologically; but it's 1 a.m.)
What's to be next? 077 in GSR livery? Oh... wait....