People often incorrectly jump to the conclusion that the dog bones are to prevent axle wrap under the severe torque of the engine or braking forces. I suppose they do serve that function to a point. But take a closer look at how the suspension actually functions in this truck.
This truck was designed to spend a lot of time moving off road with heavy loads. Regular leaf springs are very limited as to how much flex is allowed. They only go up and down a few inches. Over and over we see guys parking trucks on big stuff. I'm tralking about the guys who take a picture or post a video of the drivers side tire up on some foreign car. I'm amazed at how much flex the suspension has and the left front tire stay on the ground. Most pick ups would have the other tire hanging out in the air.
The M211/M135 trucks do this because it has 2 things. Dog bones... and 4 sets of spring shackles. Count them if you don't believe me. The dog bones hold the axle from shifting forward and backward. If you took the dog bones off and stepped on the brake while moving, the axle would shift backward. Take only the left one off, and step on the brake while moving and the left side of the axle shifts back and the truck pulls to the left.
This truck has 4 sets of spring shackles. Yep, shackles on both ends of the springs. It allows the springs to have more drop. It keeps the other front wheel in contact with the ground, good for both traction and braking. We incorrectly assume the trucks have only shackles on one end and the other end fixed like most leaf sprung pick ups.
So to recap, the current suspension is designed for more articulation. The springs are not fixed on one end and have shackles on both ends to allow for more drop. The dog bones or torque rods control front to back movement of the axle. Those huge spring rear spring mounts and the stabilizer bar running to the other side controls the side to side movement.
I'm wondering if they changed the rear shackles to a fixed mount?
If not maybe you should consider the fixed mount in the front. I rember an old CJ jeep when I was a kid. It had a "lift kit" (6" shackles) on the front. Here is something an old mechanic told me about what end of the spring pack to put shackles on:
"If the shackles are on the back, the axle would track. If the shackles are on the front axle will hunt." And it rhymes!
