Where Can I Find a Replacement 68 Dart Speaker

the sun destroys the paper cone in those speakers. Funny story... Friend had a 60? Ford Galaxie. He was cleaning her up, vacuuming and such. I dont recall what was bouncing on the speaker cone while it was playing but he asked me how to get it out. i poped the grille off with a pocket knife. In an instant the entire speaker cone went in the vacuum. OOPs :)
Bottom line , if you have a 40 yr old speaker that still plays... DONT TOUCH IT !