The eaton that sells the springs today is a different company than the one from the 60-70's. Just a coincidence on the name. They did acquire the factory drawings and do provide the better quality than the other company in the muscle game. NPD gets a huge break on them and passes it on. I have had them make me 2 sets in bare steal for rare Cougar applications. The big Cougar vendor carries the inferior spring and Eaton will sell direct T about 400 bucks per set from Eaton direct. If you buy from NPD they have an incorrect Black coating that is almost impossible to remove.