So I earmarked this
(the370.com/mic-Sirius-xm) awhile ago for when I replace my factory stereo because I didn’t want extra wires, antennas and mics. I think you can get away with reusing the antenna but I think u need still need the tuner, but if the aftermarket radio u have has the tuner built into it then might be able to get an adapter like this
Maestro-HRN-ANT-SAT1-Aftermarket-Satellite-Antenna.
A little splicing will be required but worth it in my book.
Hope this helps you out