Re: Can you use existing Sirus antenna
Yes, you can reuse the stock Sirius antenna.
Im pretty sure on all '08-'10 models the Sirius unit is built into the stock radio.
This is direct from wkjeeps.com (pages 20-26 on the PDF for '08 + installs):
2008 82210940AB Gen 2.5, Sirius Satellite Radio Installation Kit: includes antenna, wiring harness and I-sheet. Requires radio with integrated satellite radio (RES, REQ, REN or RER). Installation instructions PDF
coming soon.... 2015 Altitude - Billet Silver - Fully Loaded
Tow PKG + Park Sense + Backup Camera + Navigation + 9 Speaker Audio
Ready to install: 1.25" Boras, Gorilla Black Lugs, Overland Black Mesh,
4" Chrome Tips, Polk Center Speaker and Sylvania Ultra H11 - Lows & Fogs
Previous: 2008 WK 4x4... Recent 2014 Altitude - Billet Silver - Lemon