th350 & 700r4 = 27 spline output tail and 4 bolt pattern housing.
th400 & 4l80-e = 32 spline output tail and 6 bolt pattern housing.
205 27 spline male input with coupler sleave.
205 32 spline female input no coupler sleave.
bigger bearing on input gear also. if swaping will require machine work to fit bigger bearing.