Possible '96 F150 transmission defect?

well... its my dads truck. He was on his way to work one day last week, was letting off the clutch, and bang, the rear spline (spelling?) of the transmission cracked right down the center, and the driveshaft dropped right from the bottom of the truck.

I just want to know if anyone knows of any factory defects in the '96 F150 Manual Transmissions.

My dad said that he's drag raced, rally car raced, and while doing that has blown a lot of transmissions, but has never seen that before.

.:bump:.

what is the rear spline ? output shaft ? slip yoke ? I haven't heard of those going before. but I guess it's possible now........ let us know about this one. sounds like bad casting.