Idiot Boy here!! Pulled engine and trans from'47 and rebuilt both. So, no mystery with mating spline. Wouldn't go together.....tried for hours.....forced it and bent fingers on pressure plate. Problem???? Arm on shop crane not long enough. Solution??? Removed bumper and splash pan...both had allowed engine and trans to come out....and got a new shop crane with a longer reach!! Went together like butter!!
Conclusion..... self not the brightest bulb on the Christmas tree!!