[rms427]

The cylinder select device is on the top of the MSD 6AL box, on the opposite side of the rpm socket. Remove the phillips screw on the cover of the cylinder select device. Under the cover there should be two loops of wire. One red and the other blue. They should not be cut for 8 cylinder operation. For 6 cylinder the red loop should be cut and for 4 cylinder both the red and blue loops should be cut. So if either or both the loops are cut then your box has been modified for 4 or 6 cylinder operation. They come from the factory set up for 8 cylinder operation.