I took a look Fold3 and there a number of James King's in the USCT. The one you may be interested was 26 years old and enlisted in 1865 at Memphis, Tennessee. He was born in Yazoo County, Mississippi and his occupation was a boatman. They separated the enlisted papers from the service records. I would have to determine which one of these James King's is the right one and then link him to the unit in which he served to get an idea of rank.