When sourcing a used ambulance, you must prioritize the chassis condition and engine hours rather than just mileage, as these vehicles often idle for long periods. Key technical checks include the high-output alternator (minimum 250-amp) to support medical electronics, the dual-battery system integrity, and the oxygen piping system pressure tests. Ensure the stretcher loading system (manual or hydraulic) is compatible with your existing medical equipment and that the interior cabinetry is made of non-porous, easy-to-disinfect materials like aluminum or high-grade composites.