Drum explosion...

I've only seen one 727 explode, it was in a wheelstander called Chevy Rebellion. Blown big block chevy with a 727 behind it. Damn thing didn't even have a shield on it. It had one the next time it came around though.

Everyone is right that sprag failure causes the front clutch drum to overspeed and explode. That drum is big and heavy in a 727. I've never heard of a 904 drum exploding. And Eric my friend I've run my 904 at 600 horsepower, with 4000 rpm tranny brake launches in a 3100 pound car for years without the need to rebuild. They are a lot tougher than many people think. The Super Stock racers were using 904 guts in a 727 case many years ago and they lived up to around 850 HP. Now ProTrans out in California and Marv Ripe's A1 trans make all billet pieces for the 904 and ProTrans adapts it all into a 727 case for the Stock and Super Stock guys that have to run the original type trans case.

My personal opinion is you don't need a rear band apply valve body if you take certain precautions. Start your burnout in 2nd gear, or shift to 2nd right away. Don't race the car after a driveline failure that occured in 1st gear until you take the trans apart and inspect the over running clutch and drum. If the trans doesn't seem to be working right when taking off from a stop, don't race it, fix it first. And most importantly, do use an SFI approved shield or blanket.