A true black and a sunfaded black are the same thing, genetically. My mare is black and the ends of her forelock, mane, and tail are burnt orange. She also gets much browner in the winter.
With such a dark body, black points, and no brown patches on his muzzle, eyes, or flanks, I'm tempted to say he's just a sunfaded black. Yes, he could be a bay (but he's too dark). Yes, he could be seal brown (but he doesn't have a light muzzle, eyes, or flank). Yes, he could be a smoky black, silver black, etc... But that's all unlikely (think Occam's razor).
Do you know what color his parents are?