They say a little knowledge is a dangerous thing and to put up any list of data suggestion it is totally accurate would be foolish knowing the considerable number of experts on this Site.
So here is a Timeline I have drawn up for my own information and would welcome any corrections or additions to it.
1945- CIE formed
1946- Announcement that the railway would be converted to diesel traction
1946- D Class 301 5 entered service
1947- Dublin to Belfast Enterprise introduced
1948- Contract with Metropolitan Vickers for 6 twin engined diesel-electric locomotives cancelled but Sulzer had already delivered the engines
1949- 4 Walker diesel Railcars ordered for West Clare (narrow gauge)
1949- Dublin to Cork Enterprise introduced
1949- 60 AEC Railcars ordered
1950- AEC Railcars took over the Enterprise Service
1950-1 B Class 113 2 Sulzers entered service
1953- GNR acquired jointly by Dublin & Belfast Governments GNRB
1954- K Class 801 transferred to CIE
1955- F Class 501 5 Walker locomotives (Narrow Gauge) entered service
1955-7 A Class 001 60 MV's entered service
1956- 3 Dentz G Class diesel locomotives bought
1956- Introduction of 12 mixed traffic BRCW locomotives B101 Class using the Sulzer engines first delivered in 1948
1956-7 G Class 601 5 Deutz entered service
1957-8 E Class 401 19 entered service
1957-8 C Class 201 34 MV's entered service
1958- GNRB stock split to CIE & UTA
1960-2 Introduction of 14 Maybach E Class shunters
1961- Introduction of 15 GM locomotives B121 Class
1961- Passenger Rolling Stock livery changed from Green to Orange/Black
1962- Introduction of 36 GM diesels 141 Class
1962- G Class 611 7 Deutz entered service
1963- All Steam Traction withdrawn
1964- Flying Snail emblem replaced within 'Broken Wheel' logo.
1966- 12 GM diesels arrive 181 Class
1968-72 MV A & C Class re-engined with GM Motors
1972-3 72 AC Coaches from BR Engineering introduced in the new 'Supertrain' services
1973- AEC Stock had engines removed and used in Pull-Push configurations
1977- 18 new GM locomotives, 071 Class enter service
1984- First of the new Mark 3 coaches went into service, 'Intercity' branded.
1984- DART begins operating
1987- Logo change from CIE to 'IR' (Irish Rail)
1987- Last 24 Mark 3's adapted for Suburban work modified for Pull-Push using 121 Class
1987- 3 80 Class Railcar Sets leased from NIR for 3 years
1990- 15 BR Mark2a coaches brought from Vic Berry, Leicester, refitted in Inchicore entered service
1994- 32 201 Class GM locomotives arrive to replace the 001 Class.
1994- 16 new Railcars arrive from Tokyn -'Arrows' 2600 Class
1994- Logo change from IR to IE (Iarnrod Eireann)
1994- Two 201's went to NIR for the joint Enterprise Service
1997- New De Deitrich coaches introduced to the Enterprise Service
1998-9 26 Spanish built 2700 Class arrived 'Sparrows'
1998-9 10 new DART Units entered service
2001- 2800 Class enters service
2003-4 2900 Class enters service
2007- 22000 Class enters service