GU 4 Patrol Lock Up Clutch Shudder

Thanks for that. I don't think it would be overheating because it does this first thing in the morning while still cold. The ATF quality may be an issue but should not be as I service it myself and keep Mobil 1 fully synthetic ATF in the transmission which was put in at the 40K service so has now done 100K which is not a lot for a fully synthetic oil which has only done a small amount of light towing. Also when I put it in I fully flushed the system (12 litres) not just the 4 litres that drains from the drain plug.

The Patrol doesn't have a centre bearing and I haven't checked the u/j's but I grease them every 5000K's and they are still 'tight'. The vibe only occurs as soon as the torque convertor starts to go in to lock up. Actually it is more of a shudder than a vibration. Once it is in lock up the shudder continues which I suspect is due to the clutches slipping. When I back of the juice and let the clutch grip the shudder goes away.
Since my first post I have spoken to an auto tranny expert and have tried a product called Shudder Eliminator. Amazingly this product almost completely eliminated the shudder after 20K's driving and today I did a 500K run with hardly any noticeable shudder or the resultant vibration. I suspect though that this product is only going to be a temporary stop gap measure and in time I will have to replace the clutch plates in the torque convertor to fix the problem (until it happens again from what I hear)