Stock T56 main shaft issues???

I recently replaced my main shaft and 5/6 gear cluster due to stripping the splines off the shaft and cluster. This I can understand. I got a "updated" shaft and installed it with no problems. I make one great pass with the car, then on my second pass the shaft breaks on the launch. the break was extremely clean and I did not see any twist in the shaft. I sent it back, They would not waranty it bacause of a 9 dergee twist. My question is... Should my car have been able to break the shaft this way? I only have a few bolt on parts, a failing rear end and BFG drag radial.

Any opinons, experinces or so on??

Was it the larger Viper shaft? Never heard of any other upgrade.
I do not think it should break with 60' like in you sig.

no, it isn't the viper shaft. the only difference is the on the shaft were the 5/6 gear cluster splines, it is splined the total length of the cluster instead of only half of it. I can post pictures if someone is truly interested.

I wouldn't think a 1.9 60' would break it either. I'm pissed. A lot of time and effort wasted. I hope this shaft doesn't break.