Last October, Tom Petty died of an accidental overdose at the age of 66. Since his passing, the legendary singer-songwriter has been covered and paid tribute by countless artists. His legacy will continue on this Fall with the release of American Treasure, a boxed set comprising four CDs worth of Petty’s unreleased music. SiriusXM’s Tom Petty Radio channel broke the news today, teasing an unheard song from the collection called “Keep a Little Soul,” which dates back to 1982.

American Treasure is 60 songs in total and will include previously unreleased live and studio material, spanning from his early Heartbreakers days to the years preceding his death. The collection was put together by Petty’s daughter Adria, his wife Dana, Heartbreakers bandmates Mike Campbell and Benmont Tench, and longtime Petty engineer Ryan Ulate. A countdown clock on Petty’s website ends this Wednesday, suggesting more information to come.

American Treasure is out 9/28.