OK, I think I've got it now. I went through some more online GM catalogs, and they all seem to be saying it is called "roof reveal molding." (Under the ROOF section of the catalog, Exterior Trim) At the present time, gmpartsdirect.com has the lowest price of $48.68. I'm not sure if I'm going to pay that much for them though. I may just pull them out and paint them black myself. Thanks for the help.