Hello, I'm french, so I'm sorry for my poor english.
I have the same problem, lifted +2" and mud tires. The car run perfectly, except when I use 4x4H : there is the same weird noise at 40km/h.
Unfortunaly, I have search my hilux model on amayama and there is no speedometer cable : this is an electric captor, no cable.
I think this is the CV joint that make the noise, perhaps they are to short or they do not support the angle.
I will lower the differential before to see if that helps matters.