I have an H1 scissors jack that I have started carrying in the PW because there are times that an 8500-pound capacity low profile jack is handy. These jacks are available new and used, both USA and Chinese manufacture, at prices from $20 (if you are very lucky) to about $125 (NOS USA-built with carry bag).
Problem is that the jacks have a big pin on top that is designed to engage a jacking point on the control arms of the H1, and that pin is not readily compatible with the PW or other civilian trucks. Some guys cut off the pin and weld new jack pads on, and others make up pads from plywood drilled to fit over the pin. I just spoke with Richard at Bogert Manufacturing about offering a jack pad attachment designed for the H1 jack so that it can be easily used on other vehicles, and he's willing to fab a standard jack pad (like the one on your hydraulic floor jack) with a hole on the bottom that will fit over the pin on the H1 scissors jack. This seems to be a natural for Bogert because they make (made?) a very expensive hydraulic jack that the military used to lift up-armored H1s, so they are somewhat familiar with the pins and jacking points.
These hydraulic jacks are hand pump, and may be discontinued but were $2800 new and $1800 on eBay (before they sold out).
If anyone is interested in a group buy or multiple orders for just the jack pad to fit the H1 scissors jack, please post up here. I have no idea what this thing will cost, but it should not be too much because Bogert has their own jack pads and just needs to fit the cup on the bottom. The round steel pad will have the four nubs around the perimeter to keep it from rotating on your frame rails or diff housing, and should be sized so that it will take a standard polyurethane cover. Richard will make up a drawing as soon as I get some dimensions to him and I will post the drawing here. Multiple units should bring the price down, and I suggested that they make this a standard item on their website.