Kevin, I won't point you to the ERA site (which has a lot of very nice information on rear suspension geometry) because people tend to think I'm ERA biased to begin with.
Instead, I'll point you to someone else who I view as being a 5-star Cobra suspension genius. Tom Kirkham is on record in this forum as saying that the IRS in the original Cobras was superior to almost all of today's replicas and
superior to absolutely everything that has a live axle. You can do a search to confirm this, and if you can't find those threads, I'll do it for you (just ask
). Suffice to say that in a Cobra, a live axle is better than no axle at all, but it just pales in comparison to an IRS.