Section 208 (Automatic Transmission - ALLISON - Diagnosis): Identification: Transmission
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Transmission is identified by metal identification plate attached to right side of transmission case. See Fig 1.