No tanks but certainly armoured cars acquired from the departing British forces, such as Rolls Royce and Peerless so you can try searching for those in British service too. Lancia armoured lorries were also used a lot. Karl Martin's book Irish Army Vehicles is well worth getting your hands on. It's expensive but it has loads of info and some great pictures.
Also try searching the British Pathe archives for stills from their old newsreels. I found some pics there before but I havn't got the results on this machine - try a search for Irish revolution, Irish civil war, Michael Collins, etc.