I was towing with my L200 when I noticed the temperature guage go up to about 3/4 when it normally stays around the half way mark. I was about a mile from home so put heaters on full blast on hot the cus he had hit the top but cooled back to 3/4 when I had blowers on. I got home turned engine off. I checked water after hour and a half it was just below the low line so topped it up ran engine with cap off no bubbles or anything so put cap on. Drove car that evening for about 13 miles temperature was fine. Did same next morning all fine. That evening I got in car and windscreen misty started engine cleared window drove 200 yards went to pull away and had no power so rolled backwards to get out of main road saw alot of smoke or steam for a second turned engine off. Getting AA out today to tow me home car will start but has no power water system is empty and I noticed a pipe that isn't connected Whig was dripping water under the engine but it was so dark can't see where it should be attached. I am worried that the loss of power could be compression and head gasket has gone??

Firstly welcome ...

What year truck have you got ?

be surprised if you've lost compression to the point of not enough power to drive ... I know of a few that have had headgaskets go and drove them for ages . I'm not saying it isn't lack of compression though ....
If you have a split pipe then that does seem like your cause of overheating BUT if you had aircon on the dripping pipe could have been the aircon pipe ( I know you said you had heaters on but aircon helps clean a misty windscreen! ). The ' steam ' does indicate a massive loss of water though, guessing you lost heat in heaters too?

Best bet wait till AA get there and then report back with what he says....I'm sure the forum will be able to help................

Thank you for your reply. I am sat nervously awaiting the arrival of the AA. It's a 2005 the window cleared really quickly so didn't notice whether heaters lost temperature to be honest it all happened very quickly. The water is completely empty so yes a quick loss of alot of water. But when I tried to pull away it sounded more like a motorbike and I couldn't get any power I couldn't move at all but it still ran and idled fine. I will update you when I can thank you

if your water has gone , then it must have gone somewhere
either into the engine or straight out onto the floor
you've got either a hose off or head gasket gone
you might try looking for a air lock but 99% of the time it's the head gasket
make sure you top up the radiator not just the overflow bottle on the inner wing
bubbles in the radiator ? head gasket
bubbles in the overflow ? head gasket
I know it's not nice to hear but head gasket is the most common failure whenever overheating is concerned
worth changing the rad cap as they aren't expensive
also worth flushing the rad to make sure it's not clogged
check the radiator isn't choked with mud or the like

Thank you for all your help. It turns out the cooling system was completely empty It was just the reservoir tank that was empty. The lack of power was caused by the egr valve sticking open which the AA man sorted and i am running again. Just need to keep an eye on the water as i think i am losing a bit.

find out from where the water loss is so you dont over heat and cook the head

Did AA man find why you had steam/vapour ? That indicates a leak somewhere to me.
And your not the first to have a sticking egr valve!