Well, the ATF has decided to keep its answer on the post-sunset LEO resale issue close to the vest until the law actually sunsets.  I specifically asked about (1) legal transfer  and ownership, and (2) excise tax ramifications (including asking for clarification, if the excise tax is due on civilian transfer, on who has the burden of reporting and collecting the tax: Manufacturer, LEO seller/reseller, or civilian purchaser).  I have sent the same question in writing as well as by email, but here is the email response.  As the letter was a formal counsel request for policy clarification, it should get a formal response in writing soon.  Once I get a formal written response, I will post a privacy edited PDF for everyone here.   The last thing we need is for LEO resales to be left in the same lurch as M16 bolts in otherwise unmodified ARs (for which I am still waiting for a formal, clear answer that corresponds to the law and reflects an actual ATF policy stance).  

Here is the answer they sent me back:

"...
Thank you for contacting our Website. Enforcement
Programs and Services (EPS) has been working on a document that
will address all the issues both with the public, industry, law
enforcement, etc., if the ban expires.  The document is not yet
approved for release. Questions can not be answered until such
time as we have a final document. We have prepared Q&A's and
will be ready to respond by Sept. 13.  

So, at this point, all I can advise you is to check our Website
on Sept 13th and 14th.
..."

The ATF has now answered this question on their web site.
From the ATF Q & A....

Q: Are SAWs and LCAFDs marked “Restricted law enforcement/government use only” or
“For export only” legal to sell to civilians in the United States?

A: Yes. SAWs and LCAFDs are no longer prohibited. Therefore firearms with the restrictive
markings are legal to transfer to civilians in the United States and it will be legal for nonprohibited
civilians to possess them. All civilians may possess LCAFDs.

Wow, I think I want a lower marked for LEO only.

Quoted: Wow, I think I want a lower marked for LEO only.

Me to, a new LE Bushy M4 is in order.