Stock Sirius antenna with aftermarket head unit?
 

Can this be done? When my free subscription is up in a few months, I want a different head unit, but I'd like to keep the stock Sirius antenna if possible.

They have an SMB connection, so most decks no. You will need a tuner.

You can pop that little connector off and use it. At least with the F-150s you can

Yes, the stock Sirius antenna will work with an aftermarket radio. Although keep in mind the plug will most likely need to be modified depending on the Sirius tuner.