I can't seem to find it in the weld symbol dialog box.
What tail? The picture you included didn't come through.
Select in the this area and type.
Or if you want a tail and no text just hit space bar.
The weld symbol shouldn't have a tail unless something is going to be put in the tail. If you are just wanting the visual of the tail, you could add a space in the tail for it to show up.
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