In a frequency domain analysis of long-period seismic data, observations of free oscillation excitation amplitudes are required in addition to frequency shifts to constrain odd-degree aspherical earth structure. To determine the feasibility of incorporating such data into large-scale inversions, we have undertaken a preliminary analysis of the observed amplitudes of fundamental spheroidal mode multiplets 0Sl with 26≤l≤43 using seismograms recorded by the IDA network. For many records, the amplitudes may be significantly better fit by allowing for a systematic shift of the theoretical spherical earth nodal lines either toward or away from the epicenter. In the great-circular geometrical optics approximation, this spatial phase shift of the amplitude pattern can be asymptotically represented in terms of the minor are integral of Δ&ohgr;local-Δ&ohgr;¿ along the source-receiver path. Results from common source-receiver paths indicate consistent sampling of the structure underlying these paths. For a number of paths, the results differ significantly from the theoretical predictions of model M84A of Woodhouse and Dziewonski. ¿ American Geophysical Union 1987