Mine got wiped out last week by some drunk/texting/asleep person in the middle of the day Saturday. Had survived every snowplow until this. Originally had a Gilbraltar Jumbo Rural box attached. Pretty light sheet metal unit.
I built the mount a couple years ago. Double swing-away return to center made from schedule 40 1.5" pipe.
Trashed box. Arm detaches at the swivel. Box was in the ditch about 40 feet up the highway.
The tire tracks from the vehicle were right beside the post. WAY of the road...
I was very please to see the arm return to center, as designed, after the crazy hit it got.
Mount survived just fine. The box bolts to 2 pipe hanger brackets that slide over the pipe. I have one hanger bracket welded to a split shaft collar so I can fix the angle of the box to the pipe.
Went hunting for a new mailbox on the quick. Something more robust and found this fantastic unit built right here in Ontario. 100% plastic welded high density polyethylene (HDPE). Supposed to be baseball bat proof, good to -40 degrees, and UV stable. Very pleased with it's construction. All stainless hardware with a 1/4" rod hinge. The door hinge has a spring so the door says up when opened, and the door is very well sealed. Hope its a winner.
https://plasticweldingrepairs.ca/product-category/dura_line_rural_mail_boxes/
Managed to save my old number sign and fit it to the new box. Went with a blue box and the colors matched up really well.
Hope this version holds up for a while!