The energy gap (2∆) and transition temperature (Tc) of aluminum films in Al-insulator-M tunnel junctions was measured. The orientation and crystallite size of the aluminum film was changed for different tunnel junctions by changing the substrate and/or substrate temperature at evaporation. The second metal (M) was either aluminum or indium. It was found that the strain on the aluminum film due to differential thermal expansion could account for most of the observed variation in Tc. If M was indium, both 2∆ and Tc were changed. Empirically, it was found that Tc was increased by 3.2% and 2∆ was decreased by 3.3% owing to the indium film. This effect is not understood. The energy gaps of the aluminum films were 3.64kTc for tunneling in the  direction, 3.52kTc for tunneling in "isotropic" material, and 3.41kTc for tunneling in the  direction. This anisotropy is in approximate agreement with theoretical predictions.