I asked a question on the USCT web site. I found the following while waiting for a reply.

My great grandfather, Perry Stewart, was born in 1856 in Concordia Parish, Louisiana. I found his father, my great great grandfather, Jacob Stewart, listed with the 6th U. S. Colored Heavy Artillery, 1863 - 1866. I have obtained, and filled out, NAFT Form 85.

What's the next step?