I have to assume that you got it off. However, just to let you know that my 2016 was the same way. I think GM uses thread locker on the antenna threads. After trying penetrating fluid with no success, I discovered that the antenna itself is a threaded female and the base on the truck is a threaded male. The penetrating fluid could not even wick up into the antenna so that was a bust.Need help switching antenna on 08 silverado . Base has a place for wrench but its so tight im afraid. Its gonna break ? I mean is this normal..