[Jim Kaekel]

No disrespect intended Mike, but there are applications that do require a "pro" gear, particularly those that are high HP or heavy. I used to run a "street" gear in my '70 Olds (3770 lbs.) that has a 12-bolt, but changed to a "pro" gear after a couple of failures and recommendations from Mark Williams. Naturally, a "pro" gear doesn't have the service life of a "street" gear, but it sure beats being towed off the track. Sure, a "pro" gear is more expensive, but most of the time when a gear set fails, it takes the transmission right along with it. P.S. - Mine also has a very slight noise on coast that you can hear when the motor is shut off.