What weight of transmission fluid is used in a manual tranny for 1992 Chevy Silverado 1500?

The 1992 Chevy Silverado 1500 manual transmission doesn't use a weight designation like you'd see with motor oil (e.g., 10W-30). Instead, it uses a specific type of transmission fluid recommended by Chevrolet. The weight isn't the key factor; the type of fluid is.

You need to consult your owner's manual for the precise recommended transmission fluid for your specific transmission. The manual will list the correct GM-specified fluid type, often something like "Dexron II" or a similar designation, but it might be a more specific GM fluid type. Using the wrong fluid can severely damage your transmission.

Without knowing the exact transmission code (found on a tag on the transmission itself), it's impossible to give you a definitive answer.