68 Barracuda ragtop turn signals

My 68 Barracuda convertible's turn signals don't work. I went under the dash and found the regular 2 prong flasher and replaced it. I have 4 way flashers. I found a round flasher?? that has 3 prongs, with one of them offset from the other two. What is it for? I haven't removed the steering wheel and I want to make sure that it is necessary,. before I do. I couldn't find any other flashers under the dash. Car is a 318 auto with no special options, except for the top.