  We study numerically the disorder-induced localization-delocalization phase
transitions that occur for mass and spring constant disorder in a
three-dimensional cubic lattice with harmonic couplings. We show that, while
the phase diagrams exhibit regions of stable and unstable waves, the
universality of the transitions is the same for mass and spring constant
disorder throughout all the phase boundaries. The combined value for the
critical exponent of the localization lengths of $\nu =
1.550^{+0.020}_{-0.017}$ confirms the agreement with the universality class of
the standard electronic Anderson model of localization. We further support our
investigation with studies of the density of states, the participation numbers
and wave function statistics.
