>Not possible, at least as I understand a GUID.
>
>GUIDs are themselves generated using a number of factors, one of which is the unique (MAC?) number of a network card and have some "guarantee" to be unique across time for some billions of years or so.
>
>Maybe you can replace your existing primary key with the GUID? Much more overhead, but still at least 4 bytes less than carrying both.

Thanks for the feedback, I'll probably just add one a specific field for that.