Not trying to muddy up the discussion, but there was indeed at least ONE 440 Dart built by CHRYSLER in 1968 and there were five more, for a total of six. The one I know about is the one Dick Landy raced. I have his son Robert friended on Facebook and he's posted all about the car. So there was at least ONE. It was built by Chrysler for SS/EA class racing. Here it is.
View attachment 1716020812
Here is Paul's (RIP) thread detaining the cars.
https://www.forabodiesonly.com/mopar/threads/1968-440-gts-darts-only-6-built.217292/
So to say they didn't build them is incorrect. Thank you drive through.