List dates before choosing a year
Gather the dates shown on the complete-set plate, engine records, purchase documents and installation paperwork. Label each according to its source. An invoice date establishes when that invoice was issued; it does not by itself prove the assembled generator’s manufacture year.
Seek a set-specific confirmation
Use the exact set model, serial and specification identifiers when asking the manufacturer or an appropriate specialist for build information. Keep the response with the equipment record. Do not decode serial-number patterns using an unrelated product family or an unverified online rule.
Explain replacement-component dates
A newer engine or controller may have a different manufacture date from the original set. Record those component dates separately and describe the documented replacement event. Avoid representing the complete generator as newer simply because one visible label carries a later year.
Report uncertainty honestly
If the set year cannot be established, mark it unknown and provide the evidence that is available. You can state an earliest documented installation or ownership date with its label. Update the listing when reliable confirmation arrives, and notify active bidders if the correction affects their assumptions.