I thought there was too much infighting in the company. Dodge, usually behind in sales, always backstabbed and bickered to get their way when Plymouth was more popular, to the point in the 1970s when Plymouth started to get left behind; their upscale 1975 b-body Sebring was rebadged as a Chrysler Cordoba instead, leaving sales for Plymouth on the floor.
Dodge had the Charger, which was nice. But not much else that wasn't already covered by Plymouth or Chrysler. They didn't even have an a-body equivalent to the Barracuda, and likely wouldn't have had the Challenger either if Plymouth wasn't already gearing up for the revised 1970 platform.
In the 60's, the Fury usually outsold the Polara by over 4:1. For small cars, the Dodge Dart was copied from the Valiant but never sold as much - pick any year in the 1960s or 1970s and the Plymouth version sold 3 or 4 times as much per year.
It was Plymouth who had the idea for the economy muscle car with the Road Runner and scored big time, so Dodge tried to copy it, but sold far fewer of their Super Bees.
Plymouth scored big with the Duster in 1970, so Dodge cried "ME TOO" and got their own fastback Dart the next year, but still couldn't match sales. Look at 1974, when both models were well established: Plymouth Valiant/Duster sales were 459,083 that year while Dodge managed 109,348 for the Dart/Dart Sport versions.
After the large c-body cars were killed, Plymouth wasn't even given an R body Gran Fury until a year after Chrysler and Dodge had their versions...and the year without the Gran Fury was the first time since 1930 that Dodge managed to sell more cars than Plymouth. Every other year before then had Plymouth ahead of Dodge in sales.
Dodge didn't have anything as low priced as a Plymouth, or as luxurious as a Chrysler, so basically, Dodge should have kept making trucks and Plymouth and Chrysler could have covered the rest of the car segments just fine.
By the way, back around 1991 or so, I don't think Dodge even sold cars in Canada, just trucks and vans. If you wanted a (front wheel drive) Dodge Daytona, you bought a Chrysler Daytona. Same for a Chrysler Intrepid or Chrysler Neon. We got along fine without Dodge cars.
