So today I only got as far as stripping the block in half. Turns out I will also need a new gasket as the old one ripped apart. Parts people better have it.
Then after getting some extra circlip pliers that thing just sits in there. I got a plier that will reach out far enough but not enough leverage to take it out. Tomorrow I will add some more functionality e.g. a thread and a screw to just squeeze it together. So gearbox time has stopped until tomorrow.
I decided to service my other car instead.
Best place to get an oil cooler?
I found this place:
https://www.britishparts.co.uk/products/136286-transmission-oil-cooler-UBC760011
£136.00 - a bit expensive. The 4.4 ZF cooler is a lot cheaper.