WARNING: This page is about a different car, the 2003 GMC Sierra and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying CNG Tank Venting Kit (J-42435-A)
Courtesy of GENERAL MOTORS CORP.
Fig 2: Identifying HPL Crowsfoot - 2.5" (J-43602)
Courtesy of GENERAL MOTORS CORP.
Fig 3: Identifying Tank Removal Tool (J-45529)
Courtesy of GENERAL MOTORS CORP.
Fig 4: Identifying Combustible Gas Detector (J-45878)
Courtesy of GENERAL MOTORS CORP.
Fig 5: Identifying CNG Tank Support Harness (J-44244)