Question on ML55 AMG

[endeavor]

I bought a 2000 ML55 AMG with 88K miles, what a beast.
I did the oil change myself, by draining the oil from the
drain plug. The drain plug is close to the bushings where the
oil splashes on these bushings.
MB recommends using a vacuum pump for pumping the dirty
engine oil from the dipstick.
I put in Mobil 1 0-40W synthetic.
Also, flushed out all the brake fluid with fresh DOT4.
Am planning to change out the ATF in the transmission and also
in the power steering.
What oil is used for the gear box?
Is it regular or synthetic?
Any things that I need to be aware of this model?
Thanks
Barry