Mine has a powerglide spline..it is a COAN shaft. The reason I went with the powerglide spline is my trans guy said it was easier on him because he had to modify something to use the turbo spline...iduno. He was doing it for next to nothing as a favor AND he gave me the planetaries for it so I did as he asked.
It is rather small..I would have rather had a turbo spline..much larger diameter