The zr-1 has a wider rear end to accomodate 11 inch rear tires. It also has the lt-5 engine instead of the lt-1 on most of those vettes, and the lt-4 on the '96 anniversary edition and grand sport. The lt-5 I believe makes 405 horsepower, while the lt-1 of that time made 300 horses and the lt-4 made 330. At that time it was the fastest corvette ever made as far as top speed was concerned. The z06 has now taken the crown.