On mine I had 6 3/4 but I think it's cause its a spyder gst....thoughts?

Just another suggestion after sitting two years is checking all suspension components and ensure it's halfway aligned. I had my first dsm few years ago and when I picked it up it ran rough as hell only because it was horribly aligned.

If you really wanted to know exactly where and when your car was made/manufactured. You could always follow the VIN and track down the numbers using a VIN guide online and that will tell you when where and even what month your car was released.