Many newer style leaf springs have a bolt and nut going though the spring assembly to hold it together, rather then straps and a pin.
If the axles are turned, the bolt and nut also need to be reversed to accommodate the end of the bolt as the pin.
If not done, the head of the bolt doesn't properly serve as a sufficient pin.
I had u-bolts loosen and the alignment pin fall out or shear off and the rear axle slipped all the way to the end of the leaf spring on one side causing the 5th wheel to crab badly down the highway. This happened on I-5 practically in downtown Seattle (on the Lake Union Bridge) at 55 mph in heavy traffic. I managed to get it mostly off the road after crossing the bridge but it was un-drivable. I was VERY lucky that we didn't cause a very bad accident. Thanks to a very good and brave tow truck driver we got the axle shoved back about where it should be, tightened down the u-bolts as best we could and made it to a tire shop where they fixed it good enough to get home. I suggest that you don't go anywhere until you get this looked at! Now I check my u-bolts for tightness regularly!