Also, obtain a copy of his estate records. They usually contain an estate inventory that may list all of his slaves by name, value, and sometimes by their ages. Slaves were considered property, so when a man/woman died with slaves, they are included among the inventory of the estate, even if the person left a will or not. So, if you can't locate his will, still try to obtain his estate records from the courthouse or the Archives Dept. or through the LDS Family History Center by ordering probate and estate records on microfilm for that county.

Good Luck,
Melvin