Spoke to Rick Allison @ A&A and hes telling me that all BB 727 shafts ( splines) from 65-94 are the same for every 727. He is convinced there is some damage to the end of the shaft, mushroomed.
If the splines were different the yoke wouldnt go on at all. I've seen the 29/ 30 reference before and I think its minor splines ( root) and major ( male).
