Since peeps seem to like to bust and steal stuff, these were (offered on eBay - where I mostly shop) only $21/pr./shipped.
' might help you find the road into our place after dark...(??)

Inconveniently, they fit a FULL 4 inches by a FULL 4 inches, but (conveniently) I saved a busted yardstick, so I can shim it out easily.


One of the posts was busted underground, so Mrs. bloke and I dug out around the break, cleaned off the articulating surfaces (water/scrubbing) Gorilla-Glued them together, ran four or five 4-inch deck screws through the repair, and covered it back up. (This WORKS, and will be VERY strong. I've done this before, and results in a superb repair.)
...sharp-shooter shovel, milk jug of water, scrub brush, Gorilla Glue, 6-foot level, impact driver, deck screws, twenty minutes of time, neighbors driving by tooting their horns "hello"...
(This is an early 2000's treated post - so no rotting has occurred.)