When sourcing used light towers, the engine brand and hours of operation are the most critical factors. Prioritize reputable engines like Kubota, Perkins, or Mitsubishi as parts are globally accessible. Check the mast height (typically 20-30ft) and ensure the winch system (manual or electric) operates smoothly without fraying. For illumination, verify if the unit uses Metal Halide or LED lamps; while LED is more energy-efficient and durable, Metal Halide is often cheaper upfront in the used market.