Mission accomplished. I had tried to take it off for months while it was in my truck, would not budge even with a heat gun. This afternoon I ended up listening to some advice on here, drilling in the top and adding penetrating oil, then finally just took a hack saw to get down to the hard plastic (it was indeed super glued on) picked away at it and then smashed it with a hammer and it came off. I was able to add the boot and new knob. Yotatech community for the win!! Thanks y'all :)