Is it possible to find a M6 head?

88-89 seats. Decent condition. Front seats do not have the rails/brackets. $200.   http://i186.photobucket.com/albums/x313/gtxthunder/SDC14943.jpg http://i186.photobucket.com/albums/x313/gtxthunder/SDC14948.jpg http://i186.photobucket.com/albums/x313/gtxthunder/SDC14949.jpg http://i186.photobucket.com/albums/x313/gtxthunder/SDC14950.jpg

This was rebuilt with new serviceable u-joints from NAPA. It has maybe 1000 miles on it and comes with hardware to bolt it up to the rear. $70 plus actual shipping, paypal OK http://i154.photobucket.com/albums/s263/aiche_photos/for%20sale/IMG_20130804_103736_540_zps31d250af.jpg http://i154.photobucket.com/albums/s263/aiche_photos/for%20sale/IMG_20130804_103725_384_zps9f7311b2.jpg

My car has always made this noise, and I never thought it was a problem, but I thought I'd run it by you guys. When I decel, the exhaust makes a popping noise. It almost sounds like I'm shooting flames, but no flames come out. I've had people tell me it sounds like I'm shooting potatoes out of my exhaust. The popping only happens on decel, and it's most prominent at 2K RPM. Sometimes when I run the car hard, it'll pop aggressively at around 4k. I've got a sample video for those who are curious.