Your picture shows a slight difference in spacing at your U-Bolts, one side has a gap and the other does not... at the spring perch on your axle tube.
Your spring pack looks like it's under load and slipping sideways...
Notice how the bottom leaves are sliding off to the left?
You stack might be experiencing side load or torsion is occurring from something having slipped?
Check your set up and make certain your still in alignment. That your axle has not moved or mis aligned...
Tire wear could show axle alignment is off? How does it track going down the road?
|-----|
\-----\
I can't draw it correct here... Your wheels would not be off, but the axle would be more at an angle... with the wheels parallel.
This happened to a truck on the ranch, when the inner 2 front axle U-Bolt nots, mysteriously loosened up on the front passenger side and the axle slid forward 1/2"...
If you bent the frame with a heavy tongue load, you could have changed the geometry of the perches in relation to the spring pack, too.
How high can you jump your truck? If you know that answer... well....
The eye is definitely being force to the right by something and your bolt, (has some how), been beating diagonally against the eye socket, under load.
You might verify the other side and see if your u_bolts have loosened over there too. Check everything. Have it aligned correctly...
If your steering box is sloppy you may not be able to feel what the truck is doing when driving, just sayin'...
My exhaust and cam and spark arrestors make it so I couldn't hear my valves needed a slight adjustment...
Other thing could be is the spring rate or length is slightly different... Make certain your drive line is not hitting your case and the drive shaft is lubed up at the output splines too. If there's dirt inside your axle sleeve, then the dive shaft could be bottoming on dirt and slamming the rear axle when you bottom out and flatten the springs under load.
1/4" too little slip movement and the bushings would be getting compacted... Your shackles are supposed to prevent that from happening.
You could try to change the shackle angle so when the spring straightens out, there's still room for the shackle to move rearward, without hitting the frame.
O__________________O
O____---____--__--__O < not enough room to allow zero camber? I guess this would effect the front bushing too?
There are pictures on this forum recently of brand new set, same spring mnfg, same model number, from two different purchase orders, with significant difference in length and camber.
We always need more pictures for these
What's wrong with my Truck?" Treads...