Top view of the original Olds disc brakes.

After I got the original brakes off (and put the Band-aid on my finger from preventing the cast iron rotor from hitting the cement), you can see the Wilwood caliper mounting bracket than comes with the kit. It fit perfectly and no modifications were needed. The countersunk Allen-head fasteners are from Wilwood as well.

This is the Wilwood aluminum hub and steel brake rotor. Top quality workmanship from a company that stops a LOT of race cars.