See Figures 1, 2, 3, 4, 5, 6 and 7
The jack supplied with the Astro and Safari van is meant for changing tires during emergency roadside operations. No jack is not meant to support a vehicle while you crawl under it and work. Whenever it is necessary to get under a vehicle to perform service operations, always be sure it is adequately supported, preferably by jackstands at the proper points. Always block the wheels when changing tires.
If the van is equipped with a Positraction® (locking differential) rear axle, DO NOT run the engine for any reason with 1 rear wheel off the ground. Power will be transmitted through the rear wheel remaining on the ground, possibly causing the vehicle to drive itself off the jack.
Some of the service operations in this guide require that 1 or both ends of the vehicle be raised and supported safely. The best arrangement for this, of course, is a grease pit or a vehicle lift but these items are seldom found in the home garage. However, small hydraulic, screw or scissors jacks are satisfactory for raising the vehicle. If you are serious about home maintenance and repair, do yourself a favor and buy a quality floor jack, the convenience will pay for itself in the long run.
Heavy wooden blocks or adjustable jackstands should be used to support the vehicle while it is being worked on. Drive-on trestles or ramps are also a handy and a safe way to raise the vehicle, assuming their capacity is adequate and that there are no clearance problems with low body panels/skirts or air dams. These can be bought or constructed from suitable heavy timbers or steel.
In any case, it is always best to spend a little extra time to make sure your van is lifted and supported safely.
Before using any jack, read the manufacturer's instructions. This includes the emergency jack provided with your vehicle. When using floor jacks and jackstands, be sure they are positioned on structural components and not on body or floor panels which were not designed to support the vehicle weight (and which will just deform or break once this force is applied). Generally frame rails, differential housings and certain specified suspension components are good jacking points. For more detail, please refer to the accompanying illustrations.