I know there are a lot of variables, such as temper etc., but is there a way to quickly check the proper arc on rear leaf springs, such as spring eyes on the ground and arc up to measure the arc height. I have a set of 68' rear springs, out of a 390gt, GT package, but have no idea if the springs have taken a set/compressed. Again, is there a way to check these to see if they are good or not? Thanks. Mike