I was looking at my winshield wiper setup tonight and I have a round thingamajiggy and somehow the windshild wiper is supposed to attach to it. I've looked in Jim Carters and Chevs of the forties but cant seem to see how this setup attaches. When I turn the windshield wipers on the round thing turns. Sounds confusing but I'm just not that familiar with this. Any help on seeing how these are supposed to attach would be greatly appreciated. Thanks.