Noisy Tapetts.
The 1KD -FTV does not have easily adjustable tappets, hence its major to set tappets.
Most new vehicles have hydraulic lifters, but not the Hilux. They have Cam Followers, that cannot be shimmed, to adjust the tappets, you have to check the clearances and then purchase the correct size cam follower.
To me, that's a MAJOR fopar by Toyota, what were they thinking.