Come on now no one else is going to guess.
OK they are Leland engineering fix to a problem that they don't have, so they say. This is the first one that broke on the right rear this was 5 years ago.
This is the FIX for this one Right Rear.
Now I have another one this one is on the right front axle it is cracked all the way down one side. I found it before it broke all the way off like the other one.
I don't know if you can see the crack in the photo or not it is a brown line just above the spring hanger.
The fix for the right front.
This is two for me and I know of two more trailers that had the same thing happen.