[coyled]

Dave, I hope that you are calculating wheel rate and not spring rate. There can be a huge difference between your cobra and mine. Also, mine has an IRS, and I think you have a straight axle. Your rear rate would be way higher than mine with the same set of springs. I do not have a rear sway bar. I think my springs are 10 inch by 2 1/2 inch. But, the length and diameter does not matter only the rate. Wheel rates are what you need to figure out. Good luck, Scott.