Steel or Aluminum axle shims?

Picking up a set to see if I can get rid of my slight drivetrain vibration with the Dakars and noticed there are steel/zinc and aluminum ones offered for roughly the same price at wheelersoffroad. Any reason to pick one over the other? Hate that I didn't do this on the initial install. Oh well.

 

Get the zinc. Steel will corrode, aluminum will corrode badly when in constant contact with steel.

 

Nope. Zinc is what the OP asked about and that is actually farther from mild steel on the galvanic chart (more corrosion potential in the presence of salt water) than any series of aluminum. http://www.preservationscience.com/materials/metals/PGC.html.

Edit - and to be honest I'm not sure why that is the case

 

Did you check to see if a carrier bearing drop kit would help first? 5 minute install to check and see.

 

Already done the carrier drop. Helped, but not enough.