I've always known them as house jacks Bill. They are turned with a piece of 3/4 or 1" rod, seen rebar used. Always had to dig down some to accommodate the jacks and a 2X6 spreader on top. Not a fun job. Always a lot of crawling in and out to get what's needed but not super hard either. Getting the old out isn't too bad with enough sawzall blades. Good luck with it. The last joists I did was about 13 or 14' and we sistered 2 - 10 footers to allow us to get them on the bearing ledge on either end and stacked concrete block for an added pier to support the sisters.