Make sure all your grounds are good then go to the blower motor, pull it and bench test it, you either have a short somewhere or bad blower motor, did you every check the resistor???
An interchange manuel would not have small parts like that in it, not a hollander book anyway, I have a 66 dart I am parting and the dash has not been touched, see what diameter yours is and about how long and I might have it. Probably same thing.