I can tell you I still have the factory drum in my 63 and I do have a bolt in sprag but its not the super sprag. I do use a trans blanket and have never blown up a 727 but I dont race alot like many do. I just make sure I am aware of what I run and start my burnouts in second. And I dont roll out of the water and let the tires squeal. I let off the gas and then when the tires slow down I just idle out and then pull up and stage. Actually my brother ran low 9's at one time in his Cuda with still the stock sprag in the car and it held up fine until he changed it. I am not saying its good to run the stock drum and sprag as I am just stating that I have got away on the stock drum in what little racing I do and trying to be smart about it since I do know what can happen even though I have never blown a 727 or saw one blow up. Thats also one reason I dont race much and wont until I update the drum. Ron