A sensitive tunnel diode oscillator (TDO) technique operating at 4MHz is used to probe the dynamic response of La
3 single crystals for x = 0.125, 0.175, 0.28 and 0.33 doping. Systematics of the measured change in reactance (δX) as a function of temperature (30K < T < 320K) and DC magnetic field (0 < H < 6kOe) reveal distinct temperature and field scales associated with the dynamic response of spin. It is notable that these features are far more striking than the corresponding features in static measurements. The results are discussed in the context of structural changes leading to polaron ordering.