Yes they can be swapped.
But there have been a couple of issues.
1) The Sirius receiver is smaller than the XM received. So with longer bolts you can place the Sirius receiver in the XM spot in the trunk. You can not put the XM receiver in the Sirius spot with out some type of modifications to the metal frame in the trunk.
2) The antenna is the shark fin on the roof. Not worth it to remove the head liner and remover the shark fin. BUT....the connectors for both antennas work with each receiver. There are a few connectors on the end of the antennas, which allow you to use the antenna with each other receiver.
But our satellite signal degraded greatly, falling out repeated unless you were perfectly in clear line of sight of the sky. For example..with my XM antenna and XM receiver, I could drive down the highway under a underpass and not lose my signal. With the XM antenna and the Sirius receiver I would lose the signal driving under a cloud.
We believe this is because of the way the antennas have to be reworked to be connected into the receiver.
So...TL,DR
You'll need the Sirius receiver and the Sirius antenna and the balls to remove the headliner to swap the shark fins out.
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