I've been digging for awhile to not much success, so I figure I would try here:
I am looking for some references which compute explicitly examples of Rankin-Selberg L-functions from the constant terms of Eisenstein series (maximal and, if possible, non-maximal parabolic) attached to GL(n), for some $n>2.$
It seems that most of the references I am able to find (Shahidi, Kim, Muller, etc.) which do something of this sort do this in either for GL(2) or for general $G$.