Fulleride superconductivity is experiencing a renaissance of interest following our recent discovery of superconductivity proximate to an antiferromagnetic Mott insulating state in the expanded Cs3C60 fullerides. There is mounting evidence that the superconductivity is not of the conventional BCS type and electron-electron interactions are essential for the explanation of the observed behaviour which includes a Tc(U/W) superconductivity dome. This stands in contrast with the old key LF-muSR results on selected less expanded A3C60 fullerides in which the observation of a Hebel-Slichter peak was taken as clear evidence for conventional phonon-driven BCS superconductivity. With this proposal, we want to address the behaviour of newly available expanded fullerides Cs3-xRbxC60 which are located on the other side of the Tc(U/W) dome than Rb3C60, i.e. close to the Mott insulator-metal boundary.