v6 transmission questions

[johnny]

I understand my 97 v6 uses a t5 tranny, but im not sure what the spline is??? I understand some came with 10 spline others with 26. Im trying to find a replacement and want to make sure I get the right one. Any pointers would be awesome. Im mustang illiterate

[Herbstang]

Input Shaft = 1-1/16 inch/10 spline
Ouput Shaft = 28 Splines

26 is a GM t-5

Modern Driveline - T5 History in Ford Mustangs with specifications for World class and non-World class T5's