Abstract: A new method for deriving symmetrized expressions for the leading classical moments of spectral distributions, which characterize various anisotropic terms of the interaction potential of a pair of linear molecules, is presented. The obtained results make it possible to calculate the diffuse shapes formed by transitions between the states of the continuous spectrum of a molecular pair and allow taking into account non-Markovian effects (finite duration of binary collisions) in a rotational relaxation matrix of arbitrary rank. This procedure has also been applied to calculate the moments of vector and tensor quantities that determine the intensities of bands of the induced spectra of linear molecules. The obtained symmetrized expressions can significantly reduce the time of machine calculations.