TMS470 Die ID layout

I am trying to come up with a unique MAC Address for the RM48 processor project that I am working on.  I looked through all of the docs that I could find (trm etc.) and could not find a processor serial number or a Die ID number.  The board that I am working on will have the RM48 and a TMS470 on it.  The TMS470 has a 64 bit Die ID (High 32 bits, and Low 32 bits).  My question is what is the layout of the bits in the two 32 bit registers.  I am looking for 48 unique bits if that is available.  I have looked at the values for two of our boards and found some of the bytes were the same but broken up in different ends of the words. I am guessing that part of the ID words are revision or run ID values, and hoping that there is another part that is unique to each CPU Die.