The previous owner had tack-welded a plate over the original master cylinder hole, which was cut off and tossed away. We were lucky enough to be doing an M6 swap into an original M6 car (and had the master cylinder hole and bolt holes already in place). Since most of you'll be doing this swap into an original auto-trans car, you will need to measure and cut holes for the master cylinder and its bolts. The center of the master cylinder hole that needs to be cut is approximately 4.25 inches toward the outside of the car (from the center of the steering shaft). Height-wise, the top of the master cylinder hole is just about dead even with the top of the left-most steering shaft bolt. Drill a 1 5/8 to 1 3/4-inch hole here.