  We show that for the symmetric spaces
$\mathrm{SL}(3,\mathbb{R})/\mathrm{SO}(1,2)_{e}$ and
$\mathrm{SL}(3,\mathbb{C})/\mathrm{SU}(1,2)$ the cuspidal integrals are
absolutely convergent. We further determine the behavior of the corresponding
Radon transforms and relate the kernels of the Radon transforms to the
different series of representations occurring in the Plancherel decomposition
of these spaces. Finally we show that for the symmetric space
$\mathrm{SL}(3,\mathbb{H})/\mathrm{Sp}(1,2)$ the cuspidal integrals are not
convergent for all Schwartz functions.
