I am closing a deal to purchase a new 2010 Traverse LT but have a small problem.

The previous owner of our new used house had the insight to build a garage with a 6'-3" overhead door. The antenna of my Silverado would clip it driving in/out until I bought a shorter one. Now, I am also buying a Traverse which has plenty of roof clearance, but is about 2" short of the radio/XM/etc antenna at the rear of the roofline.

Short of rebuilding the garage, I am trying to find an alternative radio antenna to install in place of the stock one, but no one at the dealership seems to know of an alternative. All the auto-part suppliers I regularly visit online have the universal antennas which fit "all cars" but a two-foot mast that wouldn't attach to the existing base is even worse than what I have now.

So I turn to the great oracle that is the internet and ask you: any ideas?