Torque boxes.
My 72 340 Duster 4 speed 391 gears, had the front Spring halfs straped and was using a adjustable pinion snubber. Adjusted against the floor. This car would leave hard and I never Twisted the body. But it had torque boxes on it from the factory.
You can mount torque boxes on that 70 Dart and nobody would even know they're there unless they crawl underneath it and then they wouldn't know it didn't come with them. Unless it was an automatic car to start with because they didn't have torque boxes on them
