Disco 1 300tdi flex plate

My flex plate gave up the ghost this weekend, at least I'm guessing it has as I can spin it round with my finger through the starter hole.

My first question is when it let go the engine reved up of it own accord it stopped when I turned it off and there's not excessive play in the turbo shaft, there's a little oil in the inter cooler but again not exesive. Could the increase in revs be caused buy the fact the crank sensor thought the engine had stopped or was turning slower ( I guess it was probably still moving slightly) than it was?

Second question, I've not taken an auto box off before anything special I need to know about torque converters?

probably was crank sensor .its best to remove the bolts holding t/c so t/c come off with box ,then when refitting ensure t/c fits further into box by a mm or 2 than flex plate sits from rear of engine