[Jackflash]

Bear in mind that jack stands are rated for the pair, 12 ton stands only have a combined load capacity of 12 tons.  I would be uneasy getting under the rear of my rig while on 12 ton stands, it crushed the wood cribbing I tried initially.  I now have 22 ton stands and a 20 or 25 ton (can't remember for sure) air assist bottle jack.