WARNING: This page is about a different car, the 2009 GMC Canyon and 2009 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Bolt Types
Courtesy of GENERAL MOTORS CORP.
Remove the converter housing bolts (94). Use the J 41510:
T-50 plus bit for bolt (1) and DT-49037:
mortorq bit for bolt (2).