Blocks are a cheap, down and dirty, quick way to raise or lower a vehicle, but they are not the best way.
The use of blocks is the leading cause of axle wind-up and poor vehicle handling.
A vehicle is most stable when the spring seat at the axle is closest to a line drawn between the front and rear eye of the spring.
As the distance between the spring seat and this line increases, so does axle wind-up.
The more the axle rotates because of axle wind up, the less stable the vehicle will be.
For these reasons we do not recommend the use of blocks to change the ride height of any vehicle.
True, the Big 3 have used blocks on the rear of some trucks, but pay close attention to the next one you see traveling down the road.
Notice how the axle attempts to twist. This twisting happens on all vehicles as they accelerate and brake. However, the twisting is much more severe on block-equipped vehicles.
Also notice blocks are no longer used by these manufacturers.
We can manufacture leaf springs that will either lower or raise your vehicle up to 3 Inches, and coil springs that can go 2″, so why even consider blocks?