?
The element that I got has a threaded top, rubber ring, and a hex shaped bit that the insulated part is connected to. It is pretty much like this one:

Is there a fitting that is big enough to thread onto the drain pipe (1 1/2"), and also be able to allow the element piece+threaded end of the element out the top? Or does it just need a sloppy fit to the drain pipe+cap with a hole in it, then a 1" nut keep the element to the cap of the drain pipe?
So I'm looking for a 1 1/2" metal cap that fits on a drain pipe...where are these most readily found?