Here is Pettersson's Sixth, performed by Norrköping Symphony Orchestra and conducted by Okko Kamu. My favorite symphony of him, and best performance of his Sixth I've heard yet. This was released in 1976 on CBS (76553) and hasn't been reissued yet (it's kind of hard to find), so here it comes as vinyl rip. WARNING: may cause depression and various other psychical problems, or lead some people to suicides.... Enjoy!