Rear end noise

[Spook50]

Your stock diff gear is 37 x 9 teeth 4.11
80 series stock rear is 41 x 10 teeth 4.10
Aftermarket follow the 80 series convention

They are close enough, they can be run on the same truck (I do this on my FJ62)

Yeah for that close of a difference I figured there wouldn't be an issue. Didn't realize that was the reason for the shift to 4.10 though. It DOES make sense.