Hey geocacher5, I'd say you'd be much better off going with the
Yakima Lowrider roof rack system instead of messing around with the dealer install (the crossbars likely won't be rated for transporting a bike and/or other gear either. The Yakima Lowrider fits your 2006 Pontiac Montana SV6 perfectly by connecting right to the Montana SV6 roof rack side rails. The Yakima Lowider system includes four Lowrider Towers (these connect to the side rails) and two cross bars (the 48inch crossbars are the right ones for your Pontiac Montana SV6, and the crossbars are what you will connect the bike carrier to). I really like the
Yakima SprocketRocket bike rack for carrying a bike on the roof rack. The Spocket Rocket mounts right to the crossbars.