It does not appear that Arkansas Secretary of State issue separate identification numbers.
The link below provides some general information and also a phone number that you can call to confirm:
http://www.sos.arkansas.gov/bcs/documents/corporations/doing-business-in-ar.pdf
I assume you have registered appropriately with the state.
Here is another link to some FAQ's:
http://www.sos.arkansas.gov/Pages/siteSearch.aspx?q=llc
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
