I bought a set of HF 6 ton jack stands when they were on sale for like $30-40 or something and use them on my 1993 extended cab f250 diesel 4x4 with a 300lb custom front bumper and a tool box filled with probably 500 lbs of tools, chains, etc. Plus I hammered, pryed, jerked, pulled, pushed and everything in between when I installed new leaf springs and rear end and they were fine.
I also always leave the floor jack under the truck just barely touching the frame or whatever so the weights not directly on it, but will be there should the jacks fail.
Update: I'm always leery of HF stuff, so before I actually used them I tested each one individually. I jacked the truck up and one by one set them under the trailer hitch and individually they held the weight of the truck.