Linewidth distributions for single terrylene molecules in polyethylene have been measured in the temperature range from 30 mK to 1.83 K. The temperature dependence of the average linewidth is linear over the full temperature range. Linewidth distributions were simulated using the tunneling two-level system model and compared to the data in order to extract the lifetime-limited linewidth distributions and the distributions of coupling strengths between the probe molecules and the two-level systems. Differences of the average lifetime and coupling strengths were observed for samples produced with different sample-preparation techniques.