"Painless" is an oxymoron!
I have 2 67 Darts, one built in Nov 66 and one in Feb of 67.
The Nov 66 build uses a wiper motor that was also used on 66 cars. The Feb 67 uses a wiper motor used in 67.
Both are 2 speed, both are physically different from each other
BUT...
Neither looks like your...