The transfer case control module (TCM) on a 2003 Chevy Silverado isn't a single, easily identifiable box like some other modules. Instead, the control is integrated into the
body control module (BCM). Therefore, there's no separate TCM to locate. The BCM is typically located under the dash, on the driver's side. It's a fairly large module.
If you're having transfer case issues, diagnostics should focus on the BCM and associated wiring harnesses rather than looking for a stand-alone TCM.
