I would like to see the puller showing more detail, as the top is cut off in this photo. It looks like there is some alignment feature that captures the vertical "T" member.
I'm in need of this tool myself with replacing the steel posts with wood rectangular cross section treated posts.
I tried a hi-lift jack, but working by myself it was a no-go.
The '"legs" are 1/4" X 1-1/2" and the upright is 3" channel with 2 small pieces of 3/4" angle stuck on for stability, all just some pieces I had.
Here's some more pictures:
This puller allows one to pull T posts with the wire still attached to the post. It also pulls really stubborn posts.
There are many solutions on the web, I havenít seen this one. Iíll make one - I like it because it will fit anywhere on a post, slide down as needed, and the jack is easy to carry. Currently I have a bit of chain, a shackle for the wire hole and then lever the post out with a long bar and a fulcrum. Or use the tractor hydraulic lift. Both a bit cumbersome.