Sorry about the cross-posting.
I used to own what I call 'support posts'. 30 years ago I bought them at Sears. They are telescoping 3"± tubes with an acme jack screw on top. Used for either temporary or permanent support of sagging floors etc. Mine would telescope from about 5 feet to 8 feet ±. Need to buy some since I am digging a basement under my house. Can't for the life of me remember what they are called, and therefore can not find any on the web or elsewhere. I've searched under 'jack post', 'house jack', 'support post' etc.
All help appreciated.
Ivan Vegvary