The Ford auto transmissions were equiped with a 28 or 31 spline output shaft.
The rear bolt pattern to the tailhousing or transfer case adapter is different on most applications.
Ford engine blocks used three different bolt patterns. When converting vehicles with automatics, make sure you obtain a transmission with the proper bolt pattern.
The following blocks are grouped together by block bolt pattern configuration.
SMALL BLOCK FORDS: 289, 302 and 351 Windsor all have the same block bolt pattern.
FORD BLOCKS: 332, 352, 360, 390, 406, 427 and 428 all have the same block bolt pattern.
FORD BLOCKS: 429, 460, 351M and 400 all have the same block bolt pattern.
Ford then switched out and went to the Modular Ford “Coyote” Engine, this is a different pattern as well.
The links below help to identify the transmissions.