Harper says its a completely different rear end housing, I am not sure, have not looked all that carefully but I trust his opinion, cause you know he was looking for the same reason we were
I am very close to having 4.56s put in front and rear along with an ARB in the back. They will install ARB for free if installing gears. $350 for the front $300 for the rear for install. ARB costs about $800-900, rear gears are $800 right now because you can only buy OEM, front gears are $300. I have heard new aftermarket gears are almost done (2-3 months) and will be around $300.
Hope that helps.