Can anyone tell me the difference between variable rate and heavy duty rear springs, and what is best for street driving.

The variable rate springs or Cargo Coils will retain your stock ride and height. The coils of that spring are tighter towards the top to give it, its load capabilities. The heavy duty coils have a bit heavier wire in the spring. The ride will be a bit stiffer but the height should be close to stock. I would go with the Variable rate springs.

Dave

Thanks for the Quick Answer