A727 Torqueflite questions (for gurus only lol)

U need a 76 or later tranny to be able to use newer planetaries because the splines are cut on a different angle and the shaft is a little bigger. The older planetaries will not slide on the newer shafts. Then newer planetaries will slide on to the older shafts but will be loose. I haven’t tried the 5 or 6 planetaries. I have heard they will work but that’s it, I never tried it. I have t had any problems with the 3 or 4 either. Kim