Just an update:
Got a new mast from the web specifically for Lexus and it worked like a charm. Went down perfectly on the first try. So, one thing I know for sure, the generic mast from Auto Zone DOES NOT WORK. I don't know if it's too short, too long or maybe the diameter is different.
Nevertheless, I can listen to radio again :D
So I wasted $40 for two cheapies and $30 for one that worked. Oh well, live and learn. I'll know next time and hopefully my mistake will save some people a few bucks