Hi Redrange,
The nuts are threaded either M20 or M22 fine thread. I didn't realise it was the transmission cooler you were suffering with. If you are in the s**t and need to clear the threads out on the nuts, I have the taps to do the job and can post them over if you need them. It may need the steel pipe cutting to remove the nuts and clean the threads out and a 1/2" O/D compression coupler fitting to make good afterwards. If you need these I have them also.
Just send me a PM if I can help.
When I changed my engine cooler last year, I also did the transmission cooler at the same time as that was also weeping.
Same can be said about my wallet, but that's the name of the game with these P38's.