Digging for info - front drum explosion on 727s

What would cause a 727 to explode in 3rd gear at 7800 rpm? I built a 13 to 1 340 had 727 built with a manual valve body 3500 stall converter. I was building it for drag racing but my rear gear was a 3.21 so I was building a 8.75 with 3:91 gears but before I got it swapped I decided to do a top speed run with the high gears and at about 7800 the transmission exploded. Just wondering if anyone has ever experienced that before?