Bill, I know these guys have been around a long time. I have never personally dealt with them, but throughout the magazines, car site posts and general word of mouth I would certainly try them if I ever have a need. I believe they will be able to custom build a spring that is correct for your specific car with your specific options. https://www.eatondetroitspring.com/

As far as shocks, Monroe and Gabriel are decades in the business. I have used both and have been happy with both. KYB is also a prominent shock manufacturer that makes both OE style and performance shocks. I expect that in the aftermarket your shock choices will be limited to small block or big block, they will never be broken down like GM did. Don't over think it, you'll drive yourself mad!

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