H-2 NMR spectral data are reported for two types of compressed, deuterium-labeled siloxane elastomers: H-2-labeled poly(diethylsiloxane) (PDES) networks and H-2-labeled poly(dimethylsiloxane) (PDMS) free chains dissolved at low concentration in PDES host networks. We find that compressed PDES networks have higher segment orientation under stress than PDMS networks, a result that follows partially from the larger segment size (persistence length) of PDES. The internal motions of PDES chain segments are found to be substantially less isotropic than in PDMS, which leads to larger H-2 NMR line widths. Chain segments in compressed PDES elastomers have enhanced orientation compared to predictions from excluded-volume calculations. The H-2 NMR spectral splitting for compressed PDES networks is not directly proportional to (lambda (2) - lambda (-1)), unlike the case of conventional elastomers. The behavior of the compressed PDES networks is tentatively attributed to an enthalpic orientational coupling between PDES segments.