Butchiem1 said:
where can I find an XM tuner that will fit under the seat properly (that is where the connector is, right)?
The connector is only there if someone put it there.
If you bought a van with a factory XM tuner, the tuner and its connector aren't under the seat, but they're behind a panel on the side of the van, just forward of the spare tire compartment.
If you bought a van without a factory XM tuner, then the only connector is by the fusebox. There's no XM antenna anywhere on such a van. The easiest (though perhaps not cheapest) way to add XM to such a vehicle is to buy the Honda Accessory XM tuner, which comes with the tuner, wiring harness, antenna, and some brackets and hardware to put it all together. The wiring harness is needed to go from the bus connector that's near the fusebox to the connector that plugs into the XM tuner below the seat.
Install instructions that describe exactly where everything goes and how to put it there can be found on handa's site,
here. The Honda accessory XM tuner is available at any Honda dealer, or handaaccessories.com.