1964 LA/904

I just picked up a 64 LA 904 from another member. He didn’t know anything about it except for a tag zip tied to it - “Worked when pulled”. So, I understand it’s a core and it will eventually get rebuilt. Other than knowing it’s a pushbutton trans, has the rear pump with a rear support ball bearing and the ball and trunnion output flange, I am kind of clueless about pushbutton trans. Please school me on them and in particular this 64 trans.