We have studied the tunneling characteristics of Gd and Al substituted YBa2Cu3O7-δ single crystals with Tc = 90 K and 80 K respectively. The high-Tc superconductos were etched 30 min in a 1% Br solution in methanol and the tunnel barriers were formed by exposing the crystals to the ambient atmosphere for about 30 min. Pb film counterelectrodes were thermally evaporated through a metallic mask. No relevant differences have been found in the differential resistance vs voltage of undoped 90 K and Gd junctions, so confirming that Gd is substituting for Y. A different behavior has been found in the Al doped junctions that show smeared structures of reduced amplitude.