Thanks for the responses. I put on my page at
http://freepages.history.rootsweb.ancestry.com/~taleese/soldiers_rest_vicksburg/texas/riley_john/riley_john.htm

about half way down the page two enlargements of the areas of the grave marker mentioned
-- the G.A. (or C.A.)

-- and the Rifels (or Bifels)

for your remarks/comments/opinions