The old faithfull 225 slant six. The transmission is a 3 speed automatic, maybe a 904?? not real sure on that. And not sure about the rear end either but I dont think the rear end is original...its a different bolt pattern from the front. There is a clutch pedal in the car and a big hole that is now plated off in the floor so I am assuming that it was at one time a manual haha. I have a 318 in my ole dodge truck that I want to build and eventually put in the Dart and also want to go with a 4 speed manual transmission. I wish I could convert the front lug pattern to 5x4.5 like the rear is, I have a sweet set of chyrsler wheels that are almost like the ones on the general lee that I would love to put on it! I would like to find a new front seat for it but I want to stick with the bench, also plan on adding carpet and a new headliner. Then for the exterior, there are a couple small rust spots in the quarter panels that I need to get patched up and then I want to paint her back the original red color. Maybe some kind of pin stripe or two tone like I see on a lot of the other ole Darts.