Overtones of the Si-H stretching-bending polyad of the SiHD3 molecule are studied using an internal coordinate force field model. The potential parameters are optimized by fitting to the experimental band centers. The Fermi resonance between the Si-H stretching and bending motions is insignificant due to cancellation of the contributions from kinetic and potential terms. This suggests a slow redistribution of vibrational energy between these two degrees of freedom and induces local mode character of respective vibrations. Band intensities are calculated by using ah initio one- and three-dimensional dipole moment surfaces (DMS). These agree reasonably well with the observations. The successful reproduction of relative intensities between the (n(1) - 1)v(1) + 2v(5) stretching-bending combination bands and the n(1)v(1) stretching bands establishes the importance of the bending motion in the multidimensional DMS for intensity investigations.