The Torque Converter has literally ate itself and all the filings that were made during the destruction of the lock up clutch and its liner contaminated the oil with pretty severe filings which caused the valve block to malfunction i.e. valves not operating correctly not closing fully etc. which led to pressure issues which then caused the forward clutches to slip as they weren't pressed together correctly so the friction damaged them.
In my view you should change TQ every 60k miles so you don't damage the internals of the gearbox in the long run. No clutch lasts forever.
RR gearbox is driving great. Smooth shifts and seamless engagement. I've done now 300 miles on the new box, 700 odd miles to go before first oil change as I still have plenty of the Texaco juice.
The car in the meantime received a new battery which helped in some other cases.
I was being busy and gutted another 5L40E
Judging by the heat damage on the plates and the rest this gearbox was driven till it refused to move anymore as there is literally no friction material on the clutch plates.
Since then it was another trip to Automatic Choice for new plates and TQ rebuild.
Also I noticed that my Google+ managed to mess up all the photos in this thread so I will be fixing this soonish when I have a little bit more time.
Next on the list is to sell this box and buy reaming kit and some other goodies from Sonnax and be more like Phil!
I also properly flushed the tranny oil cooler. It took a while to get the clean liquid running again but now it is like new. I am not quite sure now that forking out £160 on a new cooler was a best investment but its done now.