Lets talk push button transmissions

I'm in sunny SoCal. My 65 barracuda has floor shift automatic; does that mean l can only use a 65 trans?
That depends. All 727s in 65 were a one year only cable shift slip yoke. I believe, but could be wrong, that A body 904s in 65 were still ball and trunnion flange output. If you currently have a flange output 904 you should be able to use an earlier transmission provided it has the right valve body. Just re use your existing valve body if there is an issue.