A/B Body 4 speed inside differences?

Most internals are the same. Differences seem to be year related. I feel that the newer the trans, the shift arms and lockouts got weaker and cheesier. If you are putting it in an "A" body, I'd just use the Aluminum case behind a /six. I'd put new gaskets and seals in it and run 90 wt gear oil if your budget allows. Passon Performance Transmissions can bush the aluminum case to beef it up if your is , or becomes worn.