Which /6 do I have?

Hey folks I'm new to the forum. I just purchased a 1973 Dodge Dart Sport and I'm really excited about it. There needs to be some work done to it but it runs, and for $1000, I'd say it was a steal.

Thing is, I'm not sure which engine I'm working with. I see nothing printed on the block or sides. Can anyone help me out?

I apologize if this has already been posted.