Thanks for all the responses. To answer some, it broke when I was trying to remove the nut, so I could change out the shocks. I do not know if the air shocks (on when I got the car) put to much tension on that end over time, or if it was cross threaded before, or if it was just rusted on. But when I went to remove, it broke right off. I did find a replacement, that I hope will be here today on Amazon, it is actually a Monroe part #. Some of the "universal" ones I found were too small on the threads going into the axle mount.
I was able to break it all free, and now just waiting on the new part to arrive. Thanks all!