missing antenna part

[tsanborn]

I apologize for asking something so basic but here goes. I foolishly ran my '56 Ford Country Sedan through the local car wash and (of course) broke off my antenna mast. I ordered a new mast but I now realize that I'm missing the part that threads on the bottom of the mast. Maybe if I knew what the part looks like, I'd have an easier time locating it. Note the fine threads on the bottom of the mast (attached image below) but nothing that would spin onto it to hold the mast in place without grounding it. Does anyone have a picture of what I need? If not, I'll just order a complete antenna and call it good.
https://www.fordbarn.com/forum/hamb/attach/jpg.gif