Ted, I have an old shed that has that reciever type hitch in cement. In the center of a , one piece sliding door. (slides one way) Works great, but.

In winter, if the square tubing in cement gets water down it. 2 pieces frozen.

Solution is antifreeze poured in square tubing, get rains, have to blow out water and reapply antifreeze., because too diluted.Maybe we are talking something different, but I like the pull out center reciever. Just antifreeze is toxic to animals, unless you use the RV stuff.

If I had pictures it would look like Von's galvanised pipe only square tubing that telescopes or slides inside each other, with the larger square tubing flush with cement and buried in cement,  I do not have the Morton "T" for rail, but a U shaped heavy metal piece that is on both sides of door(inside/ outside), welded on top of smaller square tubing that fits down cemented in larger square tubing.

Probably confusing everybody.