David,
I show a Louis Carriere that was in Co. F, 8th Louisiana Infantry born on the date you list (7-3-1832) but died on a completely different date ( 2-20-1874 ). He was the brother of Francois Coulon Carriere of the same company. Francois is buried in Leonville and Louis is buried in the Catholic Cemetery in Opelousas. I don't think this is the same man in the 18th because this Louis was in the 8th until Aug. 1864, when he supposedly transferred to the Navy, a fact one of his descendants disputes. The Louis Carriere in the 18th enlisted in Jan. 1862. Sorry this does not help much. I'm curious how you have a birth date that matches one record but the death date is nowhere near close. Died those dates come from Ancestry.com? Also, there is a large book on "Carriere's" at the Louisiana State Archives that has a very extensive lineage listing so you should be able to track and see which is which. I'm not sure if they have this one in the genealogical section of the Baton Rouge Public Library on Bluebonnet or not.
Wayne Cosby