Hear the first single now:
https://soundcloud.com/rappcats/jdilla-anthem

Taken from Pitchfork:

Ever since J Dilla's death in 2006, a steady stream of posthumous material has been released, with varying degrees of legitimacy. But this one is particularly huge, and totally legit: The Diary is a lost vocal album Dilla completed in the early 2000s. It's set for release via Dilla's own Pay Jay imprint (which is now managed by his family and estate) this spring. The first single, "Anthem" b/w "Trucks", is available to pre-order now, out on 12" vinyl April 15. Check out the previously unreleased A-side above.

The Diary is a collection of Dilla's raps over production by Madlib, Pete Rock, Nottz, House Shoes, Karriem Riggins, and more. However, both "Anthem" and "Trucks" feature production by Dilla himself.

According to a press release, multi-track masters of both tracks were found on two-inch tape just after Dilla's passing in 2006. They were finished by Dilla collaborator Dave Cooley for this release. The 12" features Dilla's original mix of "Trucks", which includes an extra verse and alternate vocals.

Anthem 12":
01 Anthem
02 Anthem (Instrumental)
03 Anthem (A Cappella)
04 Trucks
05 Trucks (Instrumental)
06 Trucks (Dilla's Original Mix)

Source:
http://pitchfork.com/news/49501-previously-unreleased-j-dilla-album-the-diary-announced-listen-to-new-track-anthem/