Identifying Apple Computers with the same Model Number and different builds
All older Apple computers have an uncommon and little know two factor identifier system
All Apple brand computers manufactured before Apple started to use Intel brand central processing units had a 2 factor identifier set. The Apple model number which always takes the form of Axxxx, where xxxx represents the device model or case style, and the EMC number, which takes the form of EMCxxxx, where xxxx is a number that represents the internal hardware build. With the pair of the model number and the EMC number you can identify an individual build for each model.