I'm trying to help my friend do a gear swap in his cobra. It's a '97 cobra, 8.8 rear. i know it had 3.55's stock, but the previous owner put in 3.27's. He bought a set of "brand new" Ford performance parts 3.73's off E-bay. I've spent 3 days trying to get these gears set up right. I can't get the pinion depth right. I've changed shims(from .030" up to .090") and the tooth pattern is saying the pinion is too shallow. I'm thinking the gears aren't a matched set like they should be. If anyone has done this swap could you please help us out?