Got the Dart up on a Rack. trans question

I got my 66 dart on a rack last week and found that my trans has numbers in paint pen. It made me wonder if it is original to the car or if rebuilt/replacement. the exhaust pipe fits in an odd way. Any advice would be great I have only had it since May.






I am blogging the restoration at http://66dartgt.blogspot.com/ many more photos there