Keep the complete machine model, including its suffix, next to the old-part reference. Record markings exactly as supplied and keep photographs with the same request.
List missing evidence before asking for an alternative. Useful checks may include mounting points, dimensions and the relevant manufacturer parts drawing. A similar photograph alone does not establish a match.
Before approving a quotation, ask which reference will be supplied and how the proposed match was checked. Keep that confirmation with the quantity, destination and approved quotation for future repeat orders.