I am pretty confident that this company was organized in late 1863 / early 1864, so your ancestor probably joined this company after his gunboat sank. I know that Cocke's Company was somewhat involved in the Battle of Palmito Ranch, but I don't have a list of who was actually there. I am unaware of any others.

James Franks is not on my list. What do you know about him?

Here is my fragmentary roster of members of Cocke's Company
(missing most of them I am sure):

Black, John T.
Cocke, Capt. Frederick Bird Smith (Fred), Jr.
Garner, Sam
Hellums, James Pruitt (your great grandfather)
Kirksey, Elihu Littleberry (my gg grandfather)
Porter, David M.
Roberts, Ben M.
Roberts, David Powell
Roberts, E. K.

Please let me know of any others that I am missing. I appreciate your help, and will be happy to share what I learn as well.

Randall