I used the long plastic arm that was with it ( the ones I order have two, a short and long arm). My head popper is packed away otherwise I would take a picture for you of it. I do have another prop using this motor and will take a picture of what I did and I think it is the about the same as the Headstone popper it is just laying flat not upright. I do use locking nuts or lock tight otherwise they will work loose.
Here is a video (not me)that may help.
Halloween Tombstone Popper update - YouTube
Here is a video (not me)that may help.
Halloween Tombstone Popper update - YouTube