"stall converters". Is it just me?

In your case, I'd maybe be grateful that the guy recognized it as a Mopar! Yeah, Road Runners were available with a 400 in 1972-75, remember?
You are correct sir. How could I forget? Maybe I blocked it, haha. Sometimes I do forget they made Road Runners after 1970. I shouldn't, a guy that restores Mopars in my town has a 71 Road Runner with a 440 six barrel. Beautiful.