Range Rover L322 TD6 Creaking Rear

Hi Everyone.
I have just acquired an L322 Td6 version on an 03 plate for a good price but needing a bit of work.
Was planning to most of the work myself.
The autobox changes up and down ok but has a slip slapping noise when it changes down to the lowest gear.
Planning to do a fluid and filter change but am not sure what transmission I have.
Looking on the net I believe it’s a GM but is there a way of finding out for sure?
I also have the rear suspension creaking on the OSR and knocking from the rear end when going on an uneven surface.
Guessing it’s the rear bushes but which ones could it be?
Is there right way to test or check them with the wheel removed?
Regards Mark

As always @Bemble is the gearbox guru but lots( and lots and lots) of information on here about the gearbox for your particular model. Put gearbox in the search bar and I bet 80% of the returns are about that particular box.
Sorry no idea about the bushes but @Saint.V8 , @holidaychicken or even the reprobate who is @myfirstl322 , should be able to give some input.

Thanks Gold Rover...will have a little search

most likely upper and lower hub bushes, absolute pig to change if they have been in a long time as they tend to seize in, meaning the whole rear knuckle has to come off to use a press on them. usually that also leads to new handbrake cables as they also seize into the knuckle.

Thanks for the information about the hub bushes.
I changed them in situ on an X5 I owned using the extractor tool.
Had an hour spare yesterday so I thought I would take off the OSR wheel and have a look.the creaking noise from the rear is driving me bonkers.
Trying to jack in up to raise the wheel off the floor was interesting and I could only do this after lowering the suspension while jacking at OSR jacking point and leaving one of the doors open.
To be honest all the bushes look worn but gave them all a spray with WD40 and refitted the wheel..
To my surprise the creaking has stopped.
For now anyway.
Will look into getting the bushes replaced and probably get a garage to do it.
Can anyone recommend any I live in Hornchurch Essex?
Mark