I have had the chance to work on, drive and examine a few unrestored original mopar muscle cars.

In a word, anything that could be considered "wrong" by todays standards, often was.

Paint was usually very poor, compared to modern vehicle standards. (Lots of orange peel, and runs, etc..)
Fit and finish was usually also pretty bad. Good restorer's spend a lot of time trying to get body lines, fenders and doors to fit better than they did from the factory.

Lot's of overspray, and a lot of variation existed between cars. That's why it's funny when an "expert" claims that "THIS IS THE CORRECT WAY THIS PART-CAR-PAINT MARK, ETC.., IS SUPPOSED TO BE." Never say never with an old mopar.

Also, people need to remember that folks weren't as fussy as they are now. Wind noise, rattles, squeeks, etc.., were all just an accepted part of these cars, even when they were new.

Lastly, the crazy part is how bad they generally handled. Way overweight, noseheavy and overpowered, especially for the tires and suspensions of the time.

I think people were more responsible or at least more capable generally back then. If you sold someone a hemi car on redline non radial tires today, they'd crash leaving the dealership, and there would be a class action lawsuit against the corporation.

People today are wusses.