ET back in the day when Jeep made a real truck I had a 74, J10 360 4 BBl with quadratrack loved it,,, Anyways the front leafs really took a load with the plow, and somebody got the bright idea for 1000 pound coil over springs for the shocks. And it worked like a dream,,,,, untill it didnt! And this is another reason not to lend out your toys. Ex brother in law needed the truck to move, OK so he did, and brought it back, and never said a word!
I needed to haul wood so off I go, hit a bump and the front end starts to dance all over the place,, WTH !!!!
Turns out after much thought and tons of naughty words, the shock had blown a seal and was doing nothing but looking pretty.
Those big leaf springs in the front would flex, and where the shock would dampen the movement, and since it was blown and didnt dampen anything, those coil over springs would return the movement.
And each one was amplified, till it was all over the road.
This has nothing to do with the OP, but your comment brought this to mind