OOPs! Sorry. For some reason I thought you were talking about a front wheel drive, hence the half shaft reference. Sleep deprivation is my excuse, and I'm sticking to it!
My '79 Magnum did the same thing, it was the converter. But then, I had a T350 that the converter bolts were loose for a time, and it chewed the pump drive dogs off and everything quit like that. The flex plate was cracked all to hell, too.