Global Machinery Company Sierra 1999 - Manual (Page 282)

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The tools you’ll be using include the bottle jack (A), the
wheel blocks (B), the jack handle (C), the jack handle
extensions (D), and the wheel wrench (E).
If the flat tire is on the rear of the vehicle, you’ll need to
use both jack handle extensions.
Attach the wheel wrench to the jack handle extensions
(as needed). Attach the jack handle to the jack.