Chassisworks supplies the final number in the equation. It is the distance from the outside of the frame to the wheelhub mounting surface on the A-arm suspension. In this case, it is 131⁄4 inches on each side. Taking the original 71-inch lip measurement, we subtracted both suspension widths, both hub measurements, and 8 inches for the wheel to inner fender clearance on each side to get the frame width. Here’s the math: 71 – 26.25 – 8 – 8 = 28.75 inches. After we double-checked everything, we yanked the engine.