Frontdifferenz in einem Toyota Hilux KZN165R

Hello, i have a 2004 KZN165R Hilux SR5
the problem i have is in the front end, there is a clunking noise when traveling at low speeds between 20 and 60 km/h.
the frequency of the noise is roughly every revolution of the wheels.
I have changed the wheel bearings and seals on both sides but it hasn't stopped the noise.
Also there is a delay when engauging 4WD after pressing the button on the transfer stick or selecting low range.
Could these problems be related?
This is the first hilux with fixed hubs that i have worked on (older hilux's with manual locking hubs and leaf springs are so much easier!)
Can anyone please help me
Thankyou

maybe transfer box is the problem i had similar thing
i put EP 90 GEAR OIL in greased the props and it was fine
hope this helps you