Call Kenworth with the last six of the VIN... that's the only way to know for sure. Not every single vehicle of that make and model will have the same requirements, nor will they even within the model year.
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R134a
it gets 34 miles to the gallon
Kenworth doesn't make their own engines. At various points in their history, engines from Detroit Diesel, Caterpillar, Cummins, and PACCAR, Inc. have been available. You'd need to specify which engine and what kind of condition it's in.
If you have front A/C only, then the 2001 Chevrolet Suburban requires 29 ounces of R134a. If you have dual A/C, the vehicle will need 48 ounces of R134a.
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R134a freon...................
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