Chevrolet 2002 Silverado 1500 Pickup Owner's Manual page 395

Then, follow these steps:
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5 Speed for VORTEC 4300 V6 and 4800 V8 Engines
Shown, Other Manual Transmissions Similar
1. Remove the filler plug.
2. Check that the lubricant level is up to the bottom of
the filler plug hole.
3. If the fluid level is good, install the plug and be sure
it is fully seated. If the fluid level is low, add more
fluid as described in the next steps.
6-30
How to Add Fluid
Here's how to add fluid. Refer to the Maintenance
Schedule to determine what kind of fluid to use. See
"Recommended Fluids and Lubricants" in the Index.
1. Remove the filler plug.
2. Add fluid at the filler plug hole. Add only enough
fluid to bring the fluid level up to the bottom of the
filler plug hole.
3. Install the filler plug. Be sure the plug is fully seated.