Many thanks John for all the info and for this photo reference. I've just had a close look at the photo, agreed it's a 1960s AEC Mammoth 8-legger, which is a type available in model form from EFE
The one at Ballysodare appears to have a dark green cab, possibly with a circular logo on the cab door. The body of the vehicle is grey as you say, it looks a boxy shape but it's very hard to make out what type of body it is.
The colours could be CIE, but equally could be any other firm with a green livery.
Regarding grain and flour trucks, mostly GB types but with a few Irish ones, there is a really excellent set of photos here:
https://www.trucknetuk.com/t/mainly-rank-hovis-spillers-milling/225912?page=1
The show a great variety of shapes of bulk flour bodies, as well as a nice selection of flatbeds and other types.
I'm not attempting to model Ballysodare, but the simpler Quartertown. Owned by Webbs for most of its life I have read that it was latterly part of the Ranks empire.