[1811]

I had purchased a model 2 tiller. It was on an 1811. The person I had bought it from, lived 3 hours away and brought it up to his cousins for me to pick up about 30 min away. I am having trouble mounting this on my 1811 with 3pt hitch. From what I was told, it was mounted on a 3 pt hitch without the arms, just using the bracket. What I'm finding out is that I can't get the gearbox mounting frame to mount on. It has a special handle on it that has a place for a pin at the top but I can't seem to figure it out any suggestions would be very appreciated.