That's a Superlift traction bar. Old school, but at the later end of old-school probably from the '90's or so.
More often they were the older non-adjustable solid round bar type with eye-bushings at the rear and a simple stud with stem type bushings at the front. Think "Bronco front shock" and you get the picture of the mounting type.
You could mildly adjust them by moving the location of the nuts, so i guess I should not call then non-adjustable after all.
They worked to an extent, but fell out of favor due to their typically limiting wheel travel at a time when Bronco owners were taking them off-road and looking for MORE wheel travel instead of less. Hence the advent of units like the Wrap Trap and Torque Tamer traction devices.
If you're not going to go off-roading where you need more wheel travel, I'd leave them in place because they look cool, start a few discussions, and probably do a reasonable job of reducing axle-wrap.
I can't say that they will definitely stiffen up your rear ride comfort, but anything that is mounted out-of-sync with the movement of the suspension runs that risk.
Not sure if how it's mounted is in fact out of sync, just commenting about the possibility.
The springs are not of the newer designs either. Fewer leaves (do I count 7?), old style clamps that limit travel (but still work at their jobs) and it probably rides like a buckboard anyway due to the lowermost overload springs (the super thick ones) almost touching the next spring up. Usually an "overload" spring is flatter than the rest of the pack so only comes into play when you carry a heavy load. In your case it looks like they're already touching. That big thick leaf creates a harsh ride usually.
You might measure between the top of the axle tube to the bottom of the frame rail to see how much lift they added. Original height was approx. 6" so anything above that is your lift. They could have sagged over time, even without being driven.
Can we see a pic of the rear end of the spring at the shackle?
Thanks
Paul
