Yes they are adjustable but there is less resistance for articulation. Your stock arms have a big piece of "rubber" that they are trying to twist.... the further they "twist" this rubber the more resistance is generated... These have a joint that will not put up resistance to twist. They can be a little louder over time. BUT you will gain some flexibility. It is not huge gains unless you start changing out the coil overs to something that will allow more movement... but movement withing the stock range limitations is far easier.
If you’re just swapping the arms you can get away with just lowering the tank. But you’ll still need to disconnect the fuel filler hose and I think one breather.
They are called trailing arms. there are two upper and two lower. They attach to the frame of your bronco and to the rear axle. They are what keep the rear axle attached to your bronco and allow it to move up and down. Stock they are black and round. The stock bars have a big "rubber" center the bolt goes through. These "pretty" milled billet aluminum bars big advantage is in two parts... 1) the length is adjustable allowing you to change the pinion angle of the differential and 2) the joint that the bolt goes through at the frame and or at the axle will be a different style of joint instead of "rubber" they are bearing style of joint that is easier to move.... less resistance. when I say "bearing style" I do not mean ball bearings but look up "Heim joint"....
