Just to be a contrarian here, but Irish Rail carried wagonload freight up until 2006 when the Guiness contract ended, probably the last remnant of the Liner network, with all freight thereafter being in full trainload quantities. However, a small remnant of that network remains, in the weekly wagon transfers that run to/from Inchicore and Waterford to Limerick wagon works. It often feels like Irish Rail lost the revenue earning part of the services(the Waterford wagons ran with the Castlemungret to Waterford cement in later years, and the Dublin ones with the Guiness, which in it's last months worked as a combined Cork/Limerick service, with Limerick served by an out and back trip working from LJ, often including 1-2 wheelcarrier wagons) but were still left with the cost of crew and fuel etc to operate those services!
I guess what you are really looking for is when the traditional loose coupled services stopped operating and were replaced by replacement Vac braked liner services. I think this would have been part of the Railplan 80 freight plan. I'm not sure if there are exact dates for services out there, but a trawl online might give some answers on when the replacement liner services commenced.