A frequent question I am asked concerning used parts, especially electronic modules, is how to determine the precise part number one needs. For this we need to consult the VCATS label (such as the example shown here), which can be found in the trunk (or boot if you prefer). One will likely need to look under the carpet in the spare wheel well.
Let's take a look at the body processor module (BPM), part# LNC2500CE/017 as an example as this is a part sometimes sought. The first section, LNC2500 denotes the basic part number, in this case a BPM. The next two letters CE tell us two things - the letter 'C' designates the major specification, such as the market the car was built for and/or whether it's LHD/RHD or possibly the wheelbase (LWB/SWB). One needs to make sure that number matches so in our used parts search we are seeking LNC2500Cx/xxx
The letter after the 'C' is not critical to match. It is the super session indicator so in theory one could find matching modules with letters anywhere from A-Z in that position thus if one has to choose from CB or CE, then pick the latter which would be the newer version. Finally, we need to know what the three numbers after the oblique (/) mean. In this example we have 017 which designates the level of programming the module has. Like the major specification level, the letter 'C', we need to make sure this number matches our donor part. So, in summary, for this car we would be seeking a BPM with part number LNC2500Cx/017. We're not too concerned about the value of X.