We report a demonstration of $S\ensuremath{-}I\ensuremath{-}S$ quasiparticle tunneling in c-axis oriented planar junctions consisting of YBaCuO/PrBaCuO/HoBaCuO thin film heterostructures. In the conductance curves at low temperatures well developed peaks indicative of gap structures are found at $\ifmmode\pm\else\textpm\fi{}45$ mV. The high bias conductance shows flat dependence on energy and the best quality junction has a zero-bias conductance less than 0.05 of the normal state value. We discuss our spectra in the framework of a BCS-like density of states as well as in terms of a ${d}_{{x}^{2}{\ensuremath{-}y}^{2}}$ symmetry of the superconducting order parameter.