I want to replace my stock rear springs with the original rear springs. When i get on her see sags and when she shifts hard it sags the car is all original. I changed the shocks it help, my question is i called carquest and they said the stock rear springs are cargo springs. Is that right i don't want to change the hight or ride of the car. The car has the performance suspension not sure if that was an upgrade option. This car is staying all original and i just want to get it to ride like it was new. Any help is appreciated