ACARI Drill-Free Roof Top Mounting Platform
 

I just bought one of these for my 2010 Silverado. I wanted to have a mini light bar, but didnt want to have to drill through the roof to bolt it down and I found this on another website. Instead of drilling into the top of the cab you attach this through the cab brake light hole and then drill directly into the platform, preserving the cab roof.

It looks pretty slick and appears to fit even with a back rack/pro rack (saw pictures on another website).

I wasnt sure how it attached at first, but the website seemed to answer a lot of my questions. www.acariproducts.com.