Big thing with any truck chassis/4x4 type vehicle is going to be lift height. You can get by with less, but 24" has always been my standard, which used to be standard for a 3 ton floor jack. This matched most 6 ton jack stands. Lately I've noticed most of the 3 ton jacks on the market only lift to 20-22" which kind of *****, but I guess it's close enough.
Just to give you an idea of why you'd want to lift that high:
My stock K1500 has about 12-14" of droop on the rear suspension. In the event that you need to work on the rear suspension (say to replace a spring bushing), you'll need to support the frame and let the axle hang freely. This will require lifting the rear axle pretty much to the limit of a 24" floor jack and setting the frame down on something like a jack stand that is extended about 36" off the ground.
Another situation would be doing front wheel bearings or even brakes on the same truck. Since it is IFS, you'll need to lift the center of the truck several inches higher than the center of the tire in order to get the wheel off the ground. The most sturdy place to support the truck from jackstands so you can work is right under the tow hooks under the front bumper. With the front suspension at full droop, that area of the frame is about 18" off the ground. You need a floor jack that is capable of raising to at least about 18" in order to safely get both front tires off the ground to put jack stands under the frame. You can get away with less if you place the stands under the frame rails near the firewall, but some times that isn't as steady, and it will require you to lift the truck twice to place two stands which is annoying.
A smaller jack may be capable of lifting the vehicle, but it usually isn't as steady, and usually requires a lot more work with your arm. For perspective, my 3 ton floor jacks are typically a lot of work to lift a 3/4 ton diesel truck that weighs around 8k lbs. If I were working on those more frequently, I'd probably upgrade to bigger floor jacks.
