Used BCM no good??

I was looking to get a used BCM for my buddy's 01 impala.. But i've heard they can only be used on the orginal car in which they came with... Is this true??

Thanks in advance!!

BCM are programmed for the specific vehicle they are installed in. Even the new replacements have to be programmed with VIN specific info before installation, so you cannot put a used one from another car in.