Ron,
No doubt that this is an authentic Civil War flag. But, is it
Naval or Garrison? Without some history & provennance,
it will be impossible to say which.
There are now 14 flags reputed to have been from the CSS
Alabama. Since this vessel sank in combat, in deep water, I
consider most of these claims as bogus.
By comparison, the CSS Virginia was scuttled by its crew, in
shallow water, and only three flags can be associated with it
today.

Ken Legendre