Anyone?
??.....

Torque converter is not sealed. The gearbox fluid is circulated through it by the pump in the gearbox.
I would first disconnect the cooler hoses at the gearbox and the radiator. Thoroughly blow these through with an airline to purge them of any water. Blow through the cooler part of the radiator, again, to remove any water. Use something like an old killaspray to purge these with fresh ATF, if possible.
Drop the sumps on the gearbox and discard the fluid, reassemble and refill.
As an extra precaution when refilling with the engine running I would leave off the return hose from the cooler (can't remember which one this is) until it has bled off a little fluid before stopping and reconnecting it, just to be on the safe side.
I'm sure a tiny amount of water will probably do no harm and get "breathed" out of the box as soon as it exceeds boiling point but any significant amount of water will wreck it, so it is vital that the above is done before starting the engine IMHO.
I would also suggest a second fluid change once the car has been driven and found to be OK, just to make sure.
Kevin
Thank you all for the various replies & suggestions.
I have now emptied both sumps plus the water & remaining ATF, blown through the rad pipes (rad itself was OK), and done everything to try to remove any water in the box. I have then refilled & taken the car on a short test drive, and it is working so far, but I will empty & refill the box shortly to see if there is any more water flushed into the sumps.
Q
From the above re tiny amount of water breathing out, can it actually do this ? I.e. is there a breather on the gearbox as such as I thought that the box was essentially sealed in that what ever is in the box stays in the box ? If it is essentially sealed would the steam not blow a hole in a gasket somewhere ?
Many thanks