I think I may have answered your question in a different forum, but it's probably worth mentioning here too since it would be relevant to others who might find themselves in a similar situation.
While many of these units are not restricted for civilian ownership and use, I would steer clear of any unit that does not have paperwork showing exactly where it came from. There are a lot of people out there who can tell a convincing tale about the origins of any particular unit, but the truth is that unless they have documentation showing chain of title tracing back to the manufacturer or an authorized distributor (these are listed on the BAE/OASYS website) you are taking a huge risk.
The DOD uses a two-part test to determine whether a device is considered contraband/stolen property, and therefore subject to seizure:
1. Was the particular unit ever sold to the military?
2. Does it have a DEMIL code that prohibits transfer of the item to the general public, or mandates destruction of the item upon the end of its service life.
If these two conditions are met, the item is considered contraband and they will seize the item.