Grey one - i think ... german Feldgrau?Or Gunship Grey?[Pactra/ModelMaster] Green one - somethig like a Russian Armor Green from Model Master plus European Green. I use only Acrylic.
It's grey indeed; looks to me like a medium sea grey. Markings are a licence plate with A.R.R.2 (white lettering on a black rectangle) on the hull nose and the name Slievenamon above the MG. On most pic's of the RR's of that period, you can also see a badge on both hull and turret, with the letters FF in it. This refers to the ancient pre-christian Irish warriors.
The badge is said to be that of Oglaigh na h-Eireann - Defence (Forces) of Ireland from 1922 - though the (volunteer) Dublin Brigade (Drong Atha Cliath) had similar and came before it (1914). They differed only in those words around the "belt" or garter part of the device.
The "FF" emblem stands for Fianna Fáil - mostly associated with the political party since 1926 but meaning "Warriors of Fál (Ireland)", sometimes taken as "Warriors of Destiny" the Fianna being a much-admired third century militia.
The sunburst which is included in the design is the Fianna symbol for battle. The significance of the 8-pointed star with which it is included is said to be indeterminate but I note the star of the Order of St Patrick is an 8-pointed one (the principal insignia of which mysteriously disappeared from Dublin Castle in 1907 just before a visit by the Order's Sovereign, King Edward VII) .
Fianna Fáil is enshrined in The Soldiers' Song, the national anthem of the Republic of Ireland (written 1907) the first line of which is Sinne Fianna Fáil,, simply rendered as "Soldiers are we," in the English version.
These symbols are, indeed, important and thanks Michel for bringing that one to our notice.