Picked up a sb 727. Ran the #'s on the case and it a 66 case. Did some research here and elsewhere and ran into conflicting info on weather it should be 19 or 24 splines. This one has 24. I understand they can be swapped as long as other parts from the donor are used, but I'm not sure exactly which parts. I haven't torn it down yet. Looking for info on pumps, shafts, etc so I know what to look for and correct in the event I run into miss matched parts. Any help appreciated and thanks in advance.

A '66 was originally 19-spline but it's quite common to find them updated to the 24-spline input....the input shaft and the reaction shaft support must be swapped as a pair.

From a replacement parts standpoint, the main issue would be if the swapped parts were from a '67-70 or '71-later. '71-later had different sealing rings, piston seals and front drum bushing.

Thanks for the info. I believe the support 71 up has wider bushing, any way to tell the difference on the shafts and pumps? casting #'s on the pump or stator support? I think I am going to pull it apart tonight so I can get a better idea.