I've decided to hand this job over to the pros. Technically it's not hard but the time it will take me using the tools and facilities I have make this not worth it for me.
I just did a second flush out of the old trans fluid and at least it's now the right colour.
So I'm in the process of baselining my 400,000km 99 lx470.
When i got it the transmission fluid was very nasty and burnt looking. I've dumped it and put in synthetic. Seems to be a bit quieter and shift smoother.
I've bought a kit with a filter to change. This should be pretty...