Malaysian Airways Flight 370

[Mesa]

If Malaysian Airlines kept up to date maintenance records and as stated, the tags and stamping are still in place, it will be fairly easy to identify through the aircraft's service history.
Nearly all parts on an aircraft are a serviceable items. During regular servicing or maintenance every part of the procedure including opening, removing, servicing, inspection, and replacement parts used are normally logged and signed for against the aircraft's service history along with tradesmen, trade supervisor, independent inspector doing that particular job on every single item.
If the panel or part for what ever reason is replaced, the new serial numbers on the panel are recorded in the service log. The same thing happens with other interchangeable replacement items such as various pumps, engines etc etc.
This is one of the reasons why various air authorities world wide seize the maintenance records of downed aircraft immediately they're made aware of an accident. It helps to see what was serviced and by who, identify the aircraft's particular componentry and to stop people from changing any logged information before an investigation.