I just got done replacing the 3 wire boards with 4 wire boards. I am replacing wires as I go along and this will make a good connection for a heavier gauge wire to the turn signals. I used the original holes for the three wire, built a small plate to mount the 4 wire. If you do this, just drill new holes for the 4 wire. I had to get creative with bolts and washers to avoid drilling more holes.
