Originally Posted by bmrsldrhewitt
So I had seen on a few of the websites that sell the lift kits they where bashing aluminum spacer saying the were inferior to steel and would fail and corrode and what not. How you heard of this happening to anyone or are they blowing smoke?
I heard/read some of the same points/counterpoints, but eventually I decided to still go with the aluminum because of the price and specific size/level that I wanted. The bottom line is this... In the reasonable lifetime of your truck, neither are going to present a problem. Both are structurally sound, and both have pros and cons. Steel rusts while aluminum produces a grey powdery coating as it ages with exposure to the elements. While rust will get worse and welds could break, the "corrosion" of aluminum supposedly protects it against further degradation. Alternatively, some state that while a a piece of welded steel will bend under stress, a solid aluminum block may crack. There are also arguments against aligning aluminum next to steel like pads on the axle or leaf springs. Again, in the reasonable life of your truck (or your use of your truck before you sell/trade it), there will be no material difference between steel and aluminum on the front spacers.
That said, I did choose to avoid aluminum blocks for the back and instead bought powder coated steel because of contact with the axle and leaf springs. Further, if you live in an area with frequent snow and ice, and the roads are regularly salted, I would stay away from the aluminum. If you live in a warmer climate, you can feel good about either choice.
Hope that helps.