Finally got round to sorting the lack of brakes and disappearing brake fluid on the 6x6..turns out the front left caliber is weaping fluid and has done so for some time, unbeknown to me!
The guy who drove it for the past 50k forgot to mention to the new driver that he tops up the front pot in the MC every couple of weeks..not really any visible signs of leakage as it had massed into a greasy clump of dust and mud.
Ill install a kit in the caliber tomorrow night and all should be good.