This is totally different than the 80 rear. The coupler on the 8"/8.2 lock the gear to the carrier, so they do not employ long splines like on the 80 rear. Also with our chromoly shafts and the heat treatment done to the splines, I don't think I've ever heard of an issue.
My advice is to replace with a pair of chromoly.
Nitro Chromoly Rear Axle shaft, 03+ 4runner, FJ Cruiser, Prado 120/150
The 8.2" diff is quite a bit better than the 8", I know it doesnt sound like a lot, but enough that I dont think it warrants swapping rearends FROM an 8.2 to something else. In fact it has been extremely popular for us to upgrade people from an 8" to the 8.2", enough so, we even offer the package on our website: Toyota 8.2" Replacement/Upgrade Nitro Axle Housing, For FJ Cruiser, 4runner to 2010 & Newer Style
http://www.justdifferentials.com/NPHTFJC-8-2-p/nphtfjc-8.2.htm
My advice is to replace with a pair of chromoly.
Nitro Chromoly Rear Axle shaft, 03+ 4runner, FJ Cruiser, Prado 120/150
The 8.2" diff is quite a bit better than the 8", I know it doesnt sound like a lot, but enough that I dont think it warrants swapping rearends FROM an 8.2 to something else. In fact it has been extremely popular for us to upgrade people from an 8" to the 8.2", enough so, we even offer the package on our website: Toyota 8.2" Replacement/Upgrade Nitro Axle Housing, For FJ Cruiser, 4runner to 2010 & Newer Style
http://www.justdifferentials.com/NPHTFJC-8-2-p/nphtfjc-8.2.htm
